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Report on the: Cagayan, Cebu, and Bicol regions

Note: This is a provisional copy and not the final report. Every effort has been made to provide accurate information and accreditation but there maybe some corrections needed. 

North Luzon, CAGAYAN Province, Peneblanca

Introduction and geology to the Peneblanca Region

Cave exploration in the Peneblanca region was pioneered during the 1992 Speleo Philippines expedition with the discovery of a number of caves including the Odessa Cave system currently the third longest cave in the Philippines.

The area is some 3.5 km wide on an east west axis and about 10 km long on a north south axis. The area is bounded by the Pinacanauan River in the south, and the barangay of Nabbabalayan in the east, a spine of hills to the west of the Quibal - Tumbali road and Tumbali barangay in the north. The area is divided in half longitudinally by the Quibal to Tumbali unmetalled road which continues north into the Baggao Municipality.

The area under consideration is on the west flank of the Sierra Madre Mountains which run as a spine of elevated relief on a north south axis down the eastern seaboard of North Luzon.

The geology of the area is relatively simple, although the geology of north-eastern Luzon as a whole is very complex. The geology in the immediate area consists of greywackes, shales and limestones running in bands on a north-south axis from the east coast to the provisional capital of Tuguegarao. The bulk of the Sierra Madre Mountains in this latitude consists of wide bands of greywackes and shales containing some reef limestone and remnant of volcanic activity in the form of pyroclasts. The area of speleological interest on the western flank  of the Sierra Madre exists in an approximately 3.5 km wide block of limestone bodies (of approximately the same age) at the Pinacanauan River,the block widening to some 9 km at the northern extremity of the area under consideration.

There appears to be a complete lack of major faults, these occurring further east in the shales and greywackes of the Sierra Madre.

The depth of the limestone block cannot be readily determined with the information at hand. The highest point of the limestone block north of the Pinacanauan River is some 405m above ordnance datum (mean sea level) on the east side of the limestone area, north of Nabbabalayan. Since all cave water is likely to drain ultimately to surface rivers, as opposed to the sea, and since the Pinacanauan River operates at approximately 50m at Callao Caves Resort, the maxim depth of the caves in the region can only be some 350m. It is clearly very unlikely that cave formation can commence at the highest point and terminate at the 50m mark. It seems cave development in the area north of the Pinacanauan River commences at about the 250m level, so the maximum vertical potential can only be around 200m.

The dominant hydrological feature is the Pinacanauan river which flows approximately east west through the 3km band of limestone in an impressive gorge some 2km long, about 80m wide and 80m high. The river spills out of the gorge at Callao Caves Resort onto a 2.5 km wide alluvial plain before turning south to flow parallel to the north-south limestone block. The river flows through the gorge at an altitude of approximately 50m above datum point. As is to be expected on a limestone block, surface drainage is minimal. The only significant surface drainage exists on the west side of the Quibal-Tumbali road where water flowing off the spine of molasse hills sinks into the swallet holes approximately along the line of the road itself. It seems the Quibal-Tumbali road fortuitously runs along the line of the molasse/limestone boundary. Although not yet proven it is anticipated that most of the caves in the southern part of the the area under consideration will resurge into the Pinacanauan River. Indeed some features are clearly visible in the gorge a little upstream from Callao Caves Resort and flooded caves below the river level are known to exist.

Drainage of cave water in the northern region is dominated by 3 known large resurgences.  The most westerly is known to be the water from the Odessa system and it is possible that this is not captured by the Paret River but continues north. The size of the other two resurgences indicate the possible existence of cave system(s) with the potential to far exceed the size of the Odessa System.


PA1 - Snake Pit

Surveyed length 298.1m
Surveyed to : BCRA Grade 3b

Located in a depression 100m east of the road from the first community on the road north of the Abbenditan School.

Lower Series 128m

A large entrance leads, after 20m, to the head of a 23m pitch, Don't Look Down. From the bottom of the pitch heading back leads to a static sump after 9m. The main passage, Don't Look Up, assumes tall rift like proportions typically 3.5m wide and 30m high. After 105m the water that obviously flows in the wet season goes off to the right into a mud choke. Another high skylight entrance can be approached up a short ramp.

Upper Series 170.1m

Off the right hand side of the main entrance a small hole leads to 53m of low winding passage ,occasionally intercepting the top of the lower series, to a T junction. To the right leads to an entrance after 54m and to the left leads to another slightly larger entrance after 63m. This section of the cave has been used as a phosphate mine.


PA2 - Headless Chickens Cave

Located 200m east of the Tumbali road about 1km north of the Abbenditan School, the entrance is a large slot in the ground. At the base of the scramble down into the cave proper a short passage lead off to intercept a streamway. Upstream was followed for an estimated 200m to an aven with the water issuing from the top. Downstream was followed for an estimated 400m down a series of free climbable pots to a sump. Estimated total length 650m.



Grid Reference 17% 47’ 50”   121% 50’ 10”

Located in the same depression as PT2, a small cave of about 30m terminating in a sump known to connect with PT2.


PT2 -Odessa Cave downstream continuation

Grid Reference 17% 47’ 50”   121% 50’ 10”

The continuation of Dia’s Light. The entrance is located in a dry stream bed depression and consists of a 4m climb into initially low wet passage way. Upstream continues low with many fine gours until eventually after a short distance (approx 30m) the end is blocked by a large gour, possibly the same one as found from Dia’s Light in 1992. Downstream is initially low and wet but enlarges considerably and contained several large gours with sections of swimming in between. This was followed for 170m until extremely deep water was encountered.

Halfway down the main passage a ‘dry’ high level passage went gently up for 100m to a sump.

Total estimated length 300m.

WARNING - This cave has evidence of total flooding to the roof on a regular basis. Do not enter the cave except on a cloudless day.


PT3 - Odessa Cave -Tumbali Entrance

Grid Reference 17% 47’ 40”   121% 50’ 50”

The left entrance of Python Retreat of the Odessa Cave was located at the above reference and marked PT3 to positively identify it. 700m of Odessa was resurveyed to complete missing data.

It was identified that the Odessa System is contained within approximately 2.5km northerly by 0.5km southerly surface area. In relation to the size of the Peneblanca limestones this is a comparatively small area.


PT4 - Noodle Doodle Cave

Grid Reference 17% 48’ 10”   121% 51’ 00”

Resurgence Level

This is the large resurgence assumed wrongly in 1992 to be the water from Odessa. The volume of water resurging is at least 5 times the volume observed in the Odessa Main Drain. The 4m by 4m entrance heads on a bearing of 355 degrees. Swimming out of depth for most of the cave a sump is met after 100m. An short muddy oxbow on the left hand side connects with the upper series.

 Upper Level

Around 35m above the resurgence exists numerous entrances to an extremely complicated 3 dimensional maze with some very fine formations, even some pristine arragonite, the first time to be found in the Philippines. Heading northwards through the maize leads to a terminal mud pitch and just before this a passage to the right leads to a pitch head (12m) into the river below. Estimated to be in excess of 130m not including the region near the entrance has multiple routes in 3 dimensions.


PT5 - Rifle cave

Surveyed length 203.8m

Surveyed to : BCRA Grade 3b

At the top of the hill above PT6 a short (36m) but large blind passage way continues across the valley to a small cave 31m away. Initially small and whinedy for 49m an eyehole is passed into larger passage for 36m to an entrance. Fifteen meters away its initially large continuation emerges back near the the first passage after 38m.


PT6 - Chorizo Cave

Surveyed length 74.2m

Surveyed to : BCRA Grade 4b

From the paved road in Tumbali proper, a clearing with a large  tree, which maybe a strangling fig, can be seen approx 600m to the south east. Above this clearing is a small depression containing the horizontal entrance to the cave. This was originally discovered by descending a 14m pit higher up beside a jungle trail, dropping into a 15m diameter chamber which is connected with a slightly larger entrance chamber.



PT7 - Desert Cave

Located approximately 4km from Tumbali proper, from a dry but heavily goured inlet to the river, go up over a flat elevated area to a second dry river bed, which is followed up to the entrance, a 2.5m round old resurgence.

After approximately 100m of similar sized passage a squeeze is passed followed by a dry mud sump to the top of a muddy slope, requiring a ladder. At the bottom of the ladder one drops into a static pool and after 10m of grovelling a large underground river is met. 

Upstream went 100m to a huge sump, the bottom of which could not be seen with a Q40Lite. Just back from the start of the swim to the sump a low awkward passage becomes very tight after 20m. Downstream sumps after a 5m cascade. At the top of the cascade a 2m climb into a bat infested passage leads after about 50m to before the mud sump and pitch.

Total estimated length 285.

Peneblanca Area additional information

The national museum has carried out extensive research into prehistoric remains in the caves of the Peneblanca region. A map exists and a number of caves were surveyed and the information can be obtained from:

The National Museum
Contacts: Dr Dizon (Dr of Archaeology) tel 58 26 88
               Wilfred Ronquillo, Director.

Tumbali Additional Information

One hours walk above PT7 is rumoured to be a large cave with many chambers known locally as 16 Chamber Cave. The entrance location is known by the farmer Segundino Tuliao.


Although the area has been visited twice there is no way that the full potential of the area has been realised. From the hydrology of the area and the proliferation of caves it has the potential to yield many more kilometres of cave and even larger systems than Odessa.

Speleo Philippines 95 was unable to survey all that was explored due to survey equipment failure but endeavoured to collect as much information as possible.

The success of any future expedition visits to the area lies in the quality of the research and fieldwork carried out from now on.

Total surveyed length 1276.1
Total estimated length 1495.0

South Luzon, BICOL Region


George Cordovilla, a member of the 1992 expedition, had researched and investigated several caves in his area. from the information he provided it was planned to visit the Bicol region.

A plan the limestone hills in the vicinity of Municipality of Sipicot in the province of Carmarines Sur was abandoned after arriving in the area and finding it ridden with rebels and bandits.


Mancao Cave

Surveyed length 81.8m

Surveyed to : BCRA Grade 3b

Located in the Barangay Mancao on Batan Island, in the municipality of Rapu Rapu the cave is found at the base of an impressive limestone cliff.

The cave has two entrances 22m apart. From the left hand entrance it is 81.1m to the head of a 33.5m blind pitch.


Pototan Cave

Surveyed length 1288.1m

Surveyed to : BCRA Grade 3b

Situated at Tinokawan on Batan Island, in the municipality of Rapu Rapu the cave is approx 500m to the north of the barangay Manila.

A large resurgence some 25m wide and 10m high assume large proportions for 244m until a major side passage is met. Continuing upstream a sump is met after 94m. 

The large side passage continues dry for 201.5m to a small side passage off to the right 33m in length. Continuing along the main passage another 11m long side passage is passed on right which connects with the downstream continuation of main stream which is met shortly.after 96 meters. The now stream passage continues for 226.7m in impressive passage with an abundance of bats, crayfish and crabs until shortly after a deep water swim a second sump is met. This was examined with the aid of a Q40lite and goggles but proved not to be free divable. Total passage length from junction with initial stream passage is 574.9 meters.

Returning back to where the stream was first regained the water can be followed in small passage way occasionally out of depth passing the 11m long side passage back into the main dry passage a side passage on the left is met after 74.2 meters. This side passage was followed for 107.3m along small whineding passage until it gets low. Many fine fossils may be found washed out of the base limestone on the passage floor.

Back in the main streamway after 77.1m a tight side passage is again met on the left and gets tight after 21.1m. The main streamway continues for a further 56.3m until the upstream end of the first sump is encountered. Total passage length is 202.1m.


Caves of Abella

3 Caves exist in the barangay Abella, municipality Ligao, province Albany. The limestone in the area is of extremely low quality and no more than perhaps 100m thick. Below the limestone is mudstone and shales which contributes to most of the surface geology.

Cave 1 was located on the left hand side of steep dry river bed and was merely a 10m long and 8m deep pit in the side of the hill, heavily silted and extremely terminal.

Cave 2 was a 15m through trip.

Cave 3 was a 40m horizontal passage choked at the end by mud.


The Bicol region has large reserves of Limestone of vastly different grades. The eastern seaboard was identified as an area of potential but was unrealised due to bandit activity. Other caves are known to exist on the Caramoan Peninsula, Cantanduanes Island and in Libmanan, Kulapnitan caves are home to a colony of bats numbering millions.

The potential of the area depends more upon the political situation and accessibility than quality of the limestone.



A map provided by the DENR detailed 69 ‘known’ caves in the area with some basic details on the nature of the cave and its state of destruction by stalagmite collectors.

Accommodation was provided in the Sitio Luy-A(Ginger), barangay Lamac,municipality Pinamungajan, courtesy of Phoenix Quarries Inc who kindly gave us the keys to their store shed.

Introduction and geology to the Lamac Region

All the caves are within the Uling formation which is generally a hard massive limestone, in part porous and Carolyn. The limestone exhibits a karstic topography which show common features such as cliffs, sinkholes, depressions, dolines, and of course caves. The caves are located in elevations ranging from 180m to 340m above datum (mean sea level) and situated near the boundaries of Toledo City, Pinamungajan and Naga. The area under consideration is about 3 to 8 kilometres southwest of the now defunct Atlas Mines and is accessible through the high grade unmetalled Lutopan-Pinamungajan national road.

Stal Collectors have been extremely active in the area prior to the total ban on extraction passed in 1991. No actual extractions of stal deposits were found during our time in the area as the cutters have abandoned their destructive operations, as a result of a series of confiscations, by the DENR, at several checkpoints in Lutopan, Toledo City and also a warehouse in Mandaue City in May-June 1992.  Abundant rejects and fragments were found scattered on the cave floors, while stockpiles abandoned by cutter were found near the entrances of some caves.

In Barangay Bunga where the damage was most extensive, the collectors used chisels and metal saws to cut off the materials. Chain blocks and steel cables were evidentially used together with wooden sleds to carry the larger and heavier materials out of the caves. Bamboo ladders were used to reach stalactite deposits on high ceilings.

In barangay Lamac one particular cave, the “Tinubdan sa Sinungkulan” cave which provides the only source of potable water for the barangay, was not spared by the unscrupulous collectors. This resulted in the contamination of the water source  The workings were stopped when barangay officials of Lamac blocked the cave entrance with large boulders. A warning sign was placed over the entrance to discourage future collectors. In a cave in Sitio Hunob, Barangay Lamac, a giant stalagmite about 4m to 5m high and 2m radius was found with closely spaced drill holes around its base prepared for controlled blasting.

Cave L1

Not located or explored


Cave L2

Not located or explored. Visible from Lamac but rumoured to be a rock shelter only.


Cave L2A - Tinubdan sa Sinungkulan

The main water source of the Lamac Barangay, the entrance is located by following the main stream east of the barangay up the hill to where it emerges from the base of a cliff. Local legend is that the cave is protected by fairies who guard a stone door at the entrance to the cave. In reality the entrance is partially blocked by a boulder choke. A short ladder pitch into the choke is then followed by a awkward squeeze through dodgy boulders. The locals had tried to block the entrance by filling it with rocks to prevent stal collectors from a rival barangay. 

While the two British cavers were able to pass the choke the rest of the team tried in vain. A second entrance was located in a narrow slot above and to the left of the main entrance. Access by this rout e will require the use of two ladders.

The cave is rumoured to be very long, around 3 hours to reach the end, but shows evidence of extreme flooding in wet weather. According to local sources after 4 hours of heavy rain the main entrances resurges. It is advised that this cave is not entered in unsettled weather or 24 hours after heavy rain.


Cave L3

Not located or explored. Seen from Lamac it appears to be a large roundish entrance but is rumoured to contain a chamber of perhaps 40m and then be blind.


Cave L4 to L5

Not located or explored


Cave L6

A small resurgence cave, located west of the massive entrance of cave L7. From the base of cave seven the river bed was followed downstream for a hundred meters or so until a small stream joined from the left. Follow this stream for 50m to the entrance.

For 75m the passage is predominately knee to waist deep in water with some scrambles up small climbs until a series of three ducks is met. Beyond this around a corner a 3m climb is passed and the passage continues for around 150m getting progressively smaller until a sump is met.

The cave was partially surveyed until a time restraint forced the surveying team to exit the cave.


Cave L7

Not explored. A huge rift entrance some 40m high by ten wide visible from Lamac dominates the cliff face to the east. An attempt to gain access to this was unsuccessful as extreme climbing techniques would be required to gain access. An 80m waterfall issues from the cave in prolonged wet weather even though the cave entrance is located high on the cliff.


Caves around base of waterfall.

Facing the waterfall, to the left, a small rift for 4m untill to tight. In front, a small flat out crawlway tending to the left. To the right, 35m of small passage which leads to a second entrance furhter down the valley and higher.


Cave L8

Not located or explored. Rumoured to be connected  to cave one.


Cave L9 to 16

Not located or explored


Around Cave L16

In the bottom of the valley between the road and where 16A is marked on the map two approximately 20m deep shafts where seen. These are probably choked and were undescended.


Cave L16A

Down the valley from where cave 16 is supposed to be located a small cave on the left hand side was located and marked L16A. The cave was entered for 120m heading east, mainly low and grovelly. A blind continuation of the cave can be seen on the other side of the small valley.


Cave L17

Shaft undescended 5m. Probably choked.


Cave L18

Shaft undescended 15m. Probably choked.



Surveyed length 912.5m

Surveyed to : BCRA Grade 3b

A large depression some 40m across gives access to SLEDGE cave via an impressive 22m wide by 15m high entrance. To the left of this is a cave explored in 1994 with a fabled 7 second drop. Continuing down the slope of the impressive main entrance a 3m climb down on the right, past a huge decaying wooden ramp, leads to the main passageway.

This can be followed for 82.4m passed a 4m deep hole until the passage goes up a slope to a mud choke. At the bottom of the slope on the right a small passage which has been enlarged by stall collectors leads into the cave proper for approx 40m to a 6m climb. This can be free climbed with the aid of a 10m hand line. From the bottom of the climb the passage continues typically 8m wide and 10m high for 76m with a flat mud floor until a tricky hole in the floor is met. A 4m length of tape is useful here. The passage continues in the same form for 86m to a chamber.

Another slightly larger chamber is met soon after the first and the the passage continues in the same form to the end of the cave.


Cave L20 - PALA CAVE

Surveyed length 143.9m

Surveyed to : BCRA Grade 3b

Once a very beautiful cave this has been partially damaged by stall collectors. The main entrance has a rather fine flat roof. The route through the cave to a second entrance is rather convoluted due to the proliferation of stal formations but is reasonably well worn so it is obvious to find.


Cave L20A

Half way up the track that leads to cave 20 a smaller track off to the right leads to cave L20A after about 10m. A steep slope for 15m leads to a 7m climb requiring a ladder. At the bottom of this climb the passage leads to the left and right. To the right closed down after 5m while to the left lead through a low passage to the head of a pitch more than 60m deep, not bottomed.

WARNING the pitch is very loose and requires great care.


Cave L21

Rock shelter.


Cave L22 - L23

Surveyed length 140.7m

Surveyed to : BCRA Grade 3b

The obvious continuation to cave L20 as its entrance is only 19m away. Initially the route is small but only after a few minutes the cave gains impressive dimensions with some fine stal columns. Going left leads to a large entrance (L23) while right goes to a tall 16m diameter chamber.


Cave L24

A 4m by 3m entrance descending at 45 degrees for 10 meters to a small muddy steep slope. No airflow, probably choked.


Cave L24A

A small double blind pot (7m) just east of L24.


Cave L25

Not located or explored

Cave L26 - Earthquake Cave

A very big cave, once with fine formations but now totally destroyed by stal collectors, approx 200m long. The stal collectors even blasted a roadway through the cave to aid the removal of stal.


Cave L27

A 2m by 3m entrance located behind our hut. A 2m climb up leads into a small room 15m long.


Other sites around Cave L27

Cave A - Rock shelter.

Cave B - Rock shelter

Cave C - Shaft undescended 3m.

Cave D - 50-100m from L27 on track to L90 a large 15m blind pit on left hand side


Cave L28

Surveyed length 157.8m

Surveyed to : BCRA Grade 3b

Entrance 6.4m by 6.5m hidden by undergrowth immediately behind quarry hut. Just inside a passage to the left leads to a 9m pitch into a large choked chamber while to the right a winding passage leads to a terminal chamber.


Cave L29

Surveyed length 96.6m

Surveyed to : BCRA Grade 3b

Horizontal passage leading to a big chamber.


Cave L29A

Horizontal passage uniform in size, 75.2m


Cave L30

Big chamber, 59.8m long.


Cave L30A

Horizontal with good formations, 108m


Cave L31 & L32

Not located or explored


Cave L33 - L34

A 209m through trip.


Cave L35 - L69

Not located or explored


Cave L90

A 2m wide rift more than 60m deep possibly to water.


Cave L91

A 5m deep pit to a steep mud bank descending for a further 15m. Choked.


Cave L91 area

On top of hill west of L91 a pit of approx 20m, undescended. Also to the west about 75m away a doline about 12m deep with 6m of terminal rift passage.


Cave L92 - Dick Tracy Cave

Surveyed length 296.7m

Surveyed to : BCRA Grade 3b

A 15m deep entrance pit gains access to a sloping mud chamber which leads off for 64m to a 3.5m climb up a stall flow requiring a hand line. A further 43m leads into a T-junction with the main larger passage, Highway 13 (A lucky number for Filipinos but definitely an unlucky one for the English).

To the left after 52m the passage narrows to tall rift with a slot in the floor which soon ends  at the level of the main passage. A possible way may exist below although this was not checked.

To the right the passage continues large. After 92m the passage develops a trench which becomes more pronounced until a boulder choke is met. A strong draught appears to go over the choke to a large void visible through the big boulders. It would be possible to aid climb into the void but lack of equipment prevented this. It is possible that the draught comes from another aven entrance as the void was seen to have a solid back wall. Beneath the boulder choke a 5m pitch was descended which led to a second undescended pitch with indications of a third pitch below but no airflow.


Cave L92 area

A 20m wide by 10m high entrance, about 100m back (north) from L92, which visibly partially closes down and is reported to be very short.

Cave L93

A 41m entrance shaft, choked.


Other sites around cave L93

50m heading south on track a double ~20m pit, undescended. Another 50m on same track, near an avacado tree, an entrance to a horizontal cave 10m to choke.


Cave L94

Lost it


Cave L95

Surveyed length 334.25m

Surveyed to : BCRA Grade 3b

Located in an impressive doline with three 10m sheer sides the entrance shaft is located at the far side from the climb down. A 10m pitch leads on down a steep slope to the right but quickly chokes after 22m. To the left leads though a couple of crawls dug by stall collectors to pleasant walking passage which quickly degenerates to squalid mud. After 178.35m a 2m climb requiring a 10m hand line leads to 80m of winding passage at one stage passing an approx 10m deep pit on the right until finally a large and extremely muddy, boot stealing chamber is met. Walking across this 56m long chamber takes considerable time due to the knee deep mud but the end has some exquisite dog tooth stall flows.


Other sites around cave L95

On route from L24 to L95 going south east a large entrance can be seen to the north, unvisited. On track 150m along at far side of large depression a large pit was located 5m south of path. Approx 15m deep with possible passage at bottom heading south. Some airflow.

150-200m further south east following same path a large heavily vegitated pit with two entrance, one small (1m wide) and the other one larger (4m). Dropping stones indicates that these funnel into each other and form a blind pot. 


Cave L96 - Wind Cave

Located just beyond the entrance to L19 a strongly draughting entrance in a small depression. Initially heading southward the passage veers to the east down 3 climbs of 2.5m, 3m and 3m respectively to the head of a pitch. Two ladders are required to rig the short climbs and the pitch of some 15m drops into cave L19  just before the blasted passage 80m from  the entrance.

 An excellent SRT training trip and possibly the deepest through trip in the Philippines.


Cave L97

A 5m wide pit approx 30m deep undescended, surrounded by numerous entrances from the same development. The obvious pit to the north was descended and found to be blind while the remainder is uninvestigated.


Other sites around cave L97

On route from cave L18 to L97 a large 400m long doline is passed 300m south of L18. This doline, uncharacteristically, is devoid of cave entrances except for a blind shakehole at the western end.


Cave L98 - Chilly Cave

Surveyed length 230.1m= + 43.8 (total 273.9)

Surveyed to : BCRA Grade 3b

Located in the valley south from cave L16A a large pristine cave which intersects the surface to begin with  is followed by 116.5m of clambering over formations. A level section for 113.6m eventually comes back to the surface with the continuation only 8.5m away.

The continuation goes for 43.8m passing 2 skylights to eventually choke with mud.

Other sites around Chilly cave

50m down the valley, east, of the main entrance a pit/rift on left hand side of path, unexplored.


Cave L99

Cave in the side of the doline located at the end of the valley of L16A and L98 seen from the mid point of L98. A small cave choked with mud. Unsurveyed estimated at 50-60m. (maybe).

Other sites around L99 cave

At the bottom of the doline it looks like there is a pit/rift but on inspection this looked blocked. A number of other small holes were investigated but apart from the the two which were part of chilly cave nothing of importance.


Cave L100 - Sentry Cave

Surveyed length 29.4m

Surveyed to : BCRA Grade 3b

Large entrance 4m by 9m high with a strong draught. Leads after 16.7m to an eyehole through to a high chamber with 3 avens leading presumably to the surface. There maybe a passage off to the right but this would require aid climbing. Before the eyehole a pit to the left was undescended but estimated at 15m, presumed choked.


Other sites around Sentry cave

At the bottom of the doline a pit 20m deep followed by some kind of mudbank, undescended. The obvious hole at the bottom is blind.



Although about 20 days were spent in the field we have only just scratched the surface of the caves in this area. At times it is impossible to walk more than 50m in any direction without finding another entrance. A total of 2386m  was surveyed in area.mainly in small but impressive caves. With the exception of caves L2 , L6 and L95 all of the caves visited are ancient fossil. The key to the area lies in finding the active and recently abandoned passages which must exist at a lower level. Due to the complete lack of surface drainage and sparsity of resurgences the lower levels of the system could possibly be extensive.

Go for it guys!


In all areas

  • Richard “Tanduay” Blake BEC / LAMAC Base jumpers
  • Henry “Bolo” Bennett BEC 

In Cebu, Lamac

  • Vincent “Pating” Russell Torres USCM
  • Dante “Dansoy” Del Carmen USCM
  • Edward Boysillo USCM
  • Vincent “Manoy” Villarosa USCM
  • Irwin “Yogad’z” Ginson NORMMS/Capitol Trekkers
  • Ronnel “Chico” Estrera CAMP
  • Mike O’Driscoll BEC
  • Tracy P. Tradio USCM
  • Gregory “Jing-jing” Domoni Velos USCM
  • Adolph “McGuiva” L Espina II SA-AG (Lost Boys)
  • Dennis Roy Araro SA-AG (Lost Boys)
  • LAMAC Base jumper
  • Official Honking Team.

In Cagayan, Peneblanca

  • Jun Ocampo SMOC
  • John “Snake” Devela of Bacolod
  • Richard “Chang” Guzman SMOC

In Bicol, Legazpi 

  • Ronnel “Chico” Estrera CAMP
  • George M. Cordovilla
  • Joanne 


Speleo Philippines would specifically like to express our gratitude to the following people:

In Cebu

The people of Phoenix Quarries Inc and in particular Diesdado De Jesus for overwhelming hospitality.

  • ‘Boy’ from the US Navy for being a friend
  • The DENR mines dept of CEBU City for information
  • HABAGAT Outdoor Shop for co-ordination
  • Teofilo Estrera for hospitality
  • Chico Estrera for president
  • Yogad’z for sounds
  • Pele for guiding
  • Tanny for guiding
  • Ernie for guiding / entertainment
  • The Barangay Captainess of Lamac for permission

In Cagayan, Peneblanca

  • Jun Ocampo and family for hospitality
  • Richard “Chang” Guzman and family for hospitality
  • Bonifacio Cuantero for hospitality
  • Segundina Tuliao for hospitality
  • Bong Mendosa for advice
  • Mayor Pen for boundless support
  • The DENR for Fuck

In Bicol

  • George and Joanne Cordovilla for hospitality
  • James for conversation
  • Bonifacio Vasques for mobile home
  • The climbers of Naga city