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Nam Khong, North West Thailand

For the twelfth time we waded across the Nam Khong.  Green-brown water snails slid lazily over the green-brown pebbles.  Brilliant emerald-winged damsel flies perched on floating leaves, all facing upstream like battle ready helicopters.  Squadrons of huge pond-skaters darted hither and thither, investigating our ripples, while bee-eaters and dragonflies swooped and buzzed above us, engaged in dog-fights with their prey.

It was actually a peaceful, idyllic scene; not at all war-like, but my mind kept straying back an hour or so, to when we started our journey down the river.  We had arrived at the Nam Khong bridge and police check point by public bus.  Most people on that crowded bus - Thais, hill-tribe villagers and the occasional Buddhist monk - were continuing to the border town of Mae Hong Son.  Two 'farangs' (foreigners), each with enormous packs, caused quite a lot of interest, and everybody tried to be helpful.

"On which side of the river is the path?"

"There is no path, but you could use one of these bamboo rafts."

The rafts were flat bundles of 15 to 20 foot lengths of bamboo, which are poled downstream and, maybe, hauled back up.  They are notorious for sinking, and anyway, at this time of year the the river is full of gravel shallows making navigation a drag literally.

"There is definitely a path, and it leads to a cave."

"No!  There is no cave down the river."

"Yes.  It is in the cliffs, at the head of the first tributary."

"You cannot go into any cave.  They are dark."

"We have lights.  It is O.K. Can we leave one pack here?  We will return in the morning."

"You cannot sleep in the jungle."

They were beginning to run short of deterrents!

"We have camping equipment and plenty of food."

"The mosquitoes are really bad.  You will catch malaria."

This last ditch attempt was actually quite serious, but ...

"We have pills and repellent and nets."

They eventually accepted that we were absolutely determined (and probably mad too) and my pack was deposited in a bamboo and palm shelter where it would be completely safe: the shelter also contained several members of the Police Special Force, together with their arsenal of M16 sub-machine guns, Smith and Weston .38 revolvers, and stacks of ammunition.  The surrounding hills are constantly combed for insurgents (Kuomintang and Shan United Army) and bandits.

We soon found the path, which was fairly well trodden as many of the local villagers wandered up and down the river in search of fish.  The river meanders gently, heading south in a deep valley below massive cliffs to the east.  It drains several hundred square kilometres of karst stretching right up to the Burmese border.  A number of the tributaries that join the river from the east emerge from caves in the cliffs.  Twelve river crossings, each one made to cut off a meander or avoid small cliffs and steep sections, and we had reached the first tributary down the river from the road bridge.

We followed up the stream on a vague path to the left.  The stream flowed very slowly, straight and level; mud-floored shallows under a canopy of exotic greens.  We disturbed bright orange forest birds, whose clear calls echoed amongst the trees, and a large black and white kingfisher shot away ahead of us. Chipmunks played in the branches that overhung the water.  It was quite obvious that few people ever came here.

Suddenly we carne upon deep pools of milky-blue, and in front of us the stream cascaded noisily among large, rounded boulders of limestone.  We clambered steeply up the rocks, finding ourselves at the base of a huge slope of fallen blocks.  Above the slope we could glimpse the tall, reddish cliffs that marked the edge of the limestone plateau.  There was no sign of a cave.

 

The stream was lost among the boulders, its resurgence being from dark hollows between the rocks lower down. For a while we could still hear it, churning and falling, somewhere deep within the bouldery mass, and then we were climbing on, far above it.  After half an hour steadily working our way up the slope we reached a more-or-less level section; the cliffs now towered directly above us and a yawning overhang filled our view ahead.  A short distance across the top of the slope and a great chasm opened below.  To our left the wall dropped vertically for seventy five metres to the glint and subdued rushing of the underground stream, bubbling along in the gloom.  Forty metres across to the right an easier slope led over boulders, earth and mud to a wide, sandy ledge almost at the threshold of daylight - an ideal site for a bivouac.

Tham Nam Lang (Cave of the River Lang) is Thailand's second longest cave, surveyed at nearly eight and a half kilometres. Although not of world class length, its volume is some two million cubic metres, which is certainly respectable, and its catchment is four hundred and twenty five square kilometres.  The main sink is three and a half kilometres to the east, and is impenetrable.

Having levelled and laid out our bivi site we kitted up and made our way down to the stream.  Here, close to the exit, the water has cut itself a canyon, in one part only four or five metres wide; not far above us the cave is thirty to forty metres wide, and this canyon is a quite unusual feature. For two hundred metres the passage is straight, creating a long, tall, cuboid chamber.  At the inner end the cave turns a sharp corner and the daylight can penetrate no further.  We each had three forms of lighting, and none of these were sufficient to pick out the roof except in a couple of places where it dropped to less than thirty metres. The air was full of a fine mist whose droplets reflected back our light, and millions of tiny white flies horned in on our headlights, making it worse.

The roof was a roost for large numbers of bats and swifts, and their incessant squeaking filled the cave with noise for at least the first kilometre.  They were only seen when they flew around us at head height, catching insects.

There is very little stal to be seen.  Around the entrance there is plenty in the roof but, if there is stal on the roof further in, it is too small or too dark to pick out.  Much of the rock surface is coated with a slimy, black substance, making it dangerously slippery.  It probably results from the breakdown of organic matter, both vegetable and animal; it is worst near the entrance, where bird droppings add to the problem.  Any stal is likely to be coated with black and obscured.  New stal growth, so rapid in the tropics, is always vulnerable to the incredible flooding that occurs every wet season.

In spite of this we did come across particular areas of massive stal banks and gours - just over one kilometre in, Mekhala's Palace is a fine set of large, white gours, rising tier upon tier to a level platform close to the roof.  Nearly four kilometres in, up a dry, flowstone oxbow, is a huge stalagmite, Khan Thai.

I took in my wine bag for flotation in the deep water sections, but these are only short in the initial reaches of the cave.  There are long sections of splashing in knee-deep water, or wading from waist to chest deep, while in several areas it is possible to avoid the stream altogether by traversing on slippery ledges or clambering over rocks at the sides. There are some long, gravel banks where the going is easy, which we found a great relief.

We both felt that the cave was somewhat monotonous; it is certainly not sporting.  Having got the flavour of the cave we turned back for our bivouac. The late afternoon sun shone straight into the entrance, lighting up the whole of that vast cavern.  Even so, the moist cave atmosphere had left a layer of damp on everything, and we settled in for a chilly night.  Much later, from out of the dark, the low, throaty growl of a big cat awakened Jane, and we hoped we had not ousted a tiger or a panther from its favourite -resting place.  Who said monotonous?

The end of the cave is actually some six and a half kilometres in, beyond a long section of deep water.  The stream emerges from narrow fissures and rocks, and no way on has yet been found. The main sink is a further half kilometre to the north-east, at the western end of the long Nam Lang polje. More than sixteen kilometres upstream from here the Nam Lang has already come through another cave, Tham Lot. Close by this cave is the settlement of Ban Tham ( Cave Village) and Cave Lodge, where we stayed for several days.

Throughout this north-western corner of Thailand live numerous hill-tribes; the Lisu, Lahu, Karen, Meo and Mhong are just a few.  They are essentially nomadic peoples, who neither know nor care of international boundaries.  They live by 'slash and burn' agriculture: as they move into a new area the existing vegetation, often virgin jungle or primary forest, is cut down and burned totally to make way for crops, such as rice or opium.  The land is steep, and the fields are frequently just an area of hillside, which is left un-terraced.  The soil is thin and poor in nutrients.  The goodness from the ashes of the first burn is soon used up, and the whole tribe must abandon their village and move on.

Ban Tham, like some of the neighbouring villages, seems to be unusual in this respect: the people have been persuaded by the Thai government, who have supplied water tanks and irrigation schemes, to settle down, and the village has become more or less permanent, even boasting a school and a shop.  Many of the women still wear their traditional costumes (each tribe has its own distinctive 'uniform', bright embroidery and dresses with wide double and triple borders of contrasting colours, woven hats decorated with beads and jewels, and necklaces, bangles and earrings of silver and turquoise) but a lot of the men wear western clothes - T-shirts and baseball hats.

A little below Ban Tham, perched on the craggy edge of the Nam Lang valley, Australian John Spies and his Thai wife, Diu, have built a lodge for travellers.  It overlooks the river, which meanders gently across a wide, flat valley floor.  The air is thick with the noise of cicadas and the sweet smell of ripe, jungle fruits. The horizon is limited and blurred by the blue haze of dozens of forest fires, and the heat and humidity drains away all energy.  We were glad of the wide, deep swimming hole in the river down below, when the brown skinned boys had gone fishing elsewhere and the water-buffalo had moved out.

Quarter of an hour's gentle amble down-river, past women washing clothes on the wet cobbles, and a solitary fisher collecting crustaceans in a wicker basket on her back, and over paths swept clear of leaf litter daily by Buddhist monks, brought us to a sharp bend in the river.  Ahead was an ancient wind gap but, beneath the limestone cliffs to the right, the waters ran calmly into the hillside.  This is Tham Lot, meaning 'through cave'.

The cave opening is about forty metres wide but only ten metres high.  We climbed a rickety bamboo ladder to reach a long, level platform of sand-filled gours.  These stretched away to one side of the river and, sixty metres in, rose to an area of large stalagmites overlooking the water.  The shelf ended and we dropped to an extensive gravel bank which disappeared into the darkness.  Before we finally lost the daylight of the entrance a steep slope led up to some big side galleries.

Climbing through the high, but relatively narrow archway we entered a chamber some one hundred metres long and more than tall enough to accommodate the imposing twenty metre stalagmite standing sentinel there.  Large, brown millipedes crawled over the old, flowstone floor in search of hapless beetles. Behind us various routes led up to balconies high above the stream, while ahead lay a rockfall blocking any possible exit to the hill above.

This side passage may have been an old stream route, long pre­dating the river's present course. Immediately across the river, a thigh-deep wade, more high level passages led off.  Two bamboo ladders took us up to roof level, fifteen metres above the river, onto a heavily stalagmited shelf.  The stal was quite good, though it is being damaged by frequent visitors (the only equipment required is a torch, which a local entrepreneur will happily supply - he even has a small number of tilley lamps, especially for tourists).  Although dry now, all the stal will probably be very much alive again in the wet season. The passages gradually become smaller, no more than five metres wide and deteriorating ultimately to squeezes and crawls, with some bad air in one branch.

Back in the main river passage we avoided the deeper water by walking on the long, gravel banks, and soon daylight appeared at the resurgence.  The passage, rectangular in section, varied in width from twenty to thirty metres, while the height gradually increased to twenty five metres. A big colony of bats clustered together in the centre of the roof, their little eyes glowing red in our torchlight, and a noise of screaming swifts intensified.  Large stalactites, green with mosses, festooned the ceiling near the exit.

Up on our left lay the last of the side passages, again, perhaps, a fragment of the old stream route. Two more bamboo ladders took us to an extensive shelf, layered deep with swift guano, and a single passage led narrowly through to a chamber. In the alcoves and around the edges of the chamber were the remains of long, wooden containers.  Each was dug out from a single piece of wood in the form of a cuboid box with handles at each end.  Some archaeologists believe them to be coffins - in section they are just about adequate for a body - but they are up to three metres in length.  Others have suggested that they are possibly water tanks. Certainly their age is measurable in millenia, and they represent an ancient and forgotten people who lived in or near the caves.

 

We returned to the river, past the little piles swept together by the guano collectors, and out into the fading sunlight.  The river wound itself placidly away through deep, verdant undergrowth, and trees and bushes of brilliant greens. Having swept through a thousand metres of cave the air was now moist and cool, creating a micro-climate around the cave exit. Laughing thrushes cackled amongst the leaves, and dark, secretive birds skulked along the river banks.

As dusk approached we sat and waited in the cave mouth, watching the swifts circling in the sky above. A large bat hawk swooped down from the trees, intent on supper.  The swifts began to return from their aerial hunting to their nocturnal roost in the cave. The air was soon thick with screaming, madly circling birds, for a quarter of a million of them spend every night clinging among the stalactities.  Some tore into the darkness, only to turn at some incredible speed and sweep just above the underground river, dipping in their beaks for a momentary drink.  After an hour the cacophony had died away, and the last, late swifts spiralled down from the heavens to find their appointed spot in the roof of the cave. We returned to the lodge through the cave, and along the dark paths, listening to the night orchestra of crickets and geckos.

East of Ban Tham about seven kilometres lies the village of Ban Mae Lana.  This is another fairly permanent settlement, for it stands on some raised ground in a large, level floored polje.  Like most poljes, the soil is rich and fertile, and the nutrients are renewed seasonally.  The floor is divided up as well ordered farmland. A river, the Nam Mae Lana, flows from the north and sinks towards the southern end of the polje.  The sink is impenetrable, for the annual floods wash down huge quantities of sediment, along with bits of trees, including whole trunks.

A ridge of limestone separates the Mae Lana polje from a deep, closed depression a little to the south. This doline is two kilometres long and one wide, and the Nam Mae Lana is seen again in the bottom.  In the dry season it is no more than a little stream, and is first seen at the bottom of a fifteen metre deep hole in the limestone. Further south, but still in the doline, the stream resurges from a rock-pile, flows for a few hundred metres through bamboo forest, and enters a cave in the west wall of the doline. This is Tham Nam Mae Lana, and was the highlight of our caving in Thailand.

A brief topographical study suggests that the Mae Lana stream should continue its southward course and resurge at the Nam Lang polje, only two kilometres further south.  In fact it heads west, meandering underground for seven kilometres to cover the five kilometres across to the Nam Khong valley. Twelve kilometres of passage are now known in Tham Nam Mae Lana, making this cave the longest in Thailand.  It was our intention to do a through trip, inflow to resurgence.  Only two people had done this before, two 'hard' Tasmanians who also helped to explore and survey the cave, in May '86.

John Spies discovered the cave in early 1986 and he probably knows more about it than anyone else.  He had lots of useful advice, of which we only rejected one item - that the cave was too dangerous an undertaking for only two people, neither of whom was familiar with the system.  He tried his best to put us off (in blissful ignorance of the B.E.C. motto), but when he realized that we were absolutely determined he was extremely helpful.

He suggested various, easily identifiable features as an aid to route finding, and we were able to study the original, full scale survey two metres of paper.  More importantly he drew from memory a detailed map of the walk out from the cave resurgence back to the nearest road.  Without this we could have faced several hours', or even days', walking on a compass bearing through teak forest, scrub and jungle, searching for a way up the cliffs and back onto the plateau.  Someone else at the lodge lent us their day pack to carry gear and food underground, and we packed it with boiled rice, noodles and veges, banana cake and buns, carbide and numerous batteries, all carefully triple wrapped in poly bags.  We were taking no chances.

From Ban Tham we travelled by Land Rover over the rough forest track to Ban Soppong, a colourful, lively village that acts as a meeting point for the various hill-tribes.  On the main road west, the so-called 'short', hilly route from Chiang Mai to Mae Hong Son, we used a combination of local buses and hitched rides, one with a learner driver and the other on the back of a lorry amongst rolling drums of leaking diesel.  This last would have been fine, had the driver not been Nicki Lauda's cousin, and had the road not been a playground for diggers, bulldozers, tree­fellers and rock smashers, all trying to improve the old Japanese war-time route to Burma.

It is really good to walk after these sorts of lifts, and we left the main road for a side track (actually in much better condition than the former) to Ban Mae Lana.  The track wound slowly downwards and the jungle thinned to offer extensive views of tower karst and big dolines.  A little bamboo and thatch village appeared, set against a magnificent backdrop of two enormous, perfectly proportioned towers.  The doline and polje of Mae Lana dropped away to our right, but we had to skirt the cliff edge of these for several kilometres before reaching the polje floor at Ban Mae Lana.

The rice fields were rock hard and dry, and the stream practically non-existent.  We would be visiting the cave in ideal conditions. There was not a cloud in the sky and the threat of impending monsoon, when it rained a few days earlier, had vanished.  Crossing the low ridge between the polje and the doline, we descended first through stone forest, then across a hot, dusty area of still smouldering, blackened tree stumps, and finally steeply among bamboo, whose dry, pale-brown leaves crackled under our feet.  The little stream brought a welcome coolness to the heavy, still air, and we paddled our way along it to where it was swallowed through the three metre square entrance to Tham Nam Mae Lana.

We entered the cave soon after midday, and everything was comfortably familiar.  Only a few days previously we had covered the first couple of kilometres of cave, and had explored and surveyed a further kilometre of side passage and large chambers.  For the first two and a half kilometres it is generally easy going, following the stream, often in passage fifteen to twenty metres high and wide. There is just one slightly awkward boulder pile three hundred metres in, involving a bit of boulder balancing and simple climbing.  Occasionally the passage roof soars (as side avens) to thirty metres and more, accommodating long fluted columns of stal.  These are probably pouring with water in the wet season, but the cave, like so many in this area, is inaccessible then.  There is very little stal down the main stream-way, except for a few massive flows and gours; the annual floods quickly destroy the delicate formations that are created so rapidly only months earlier.  Several hundred metres downstream the roof dips with a heavy inflow of calcite-rich water forming a portcullis between one and two metres above the floor.  Most of the stalactites are rounded and abraded by gravel laden waters of the wet-season stream, and are blackened with organic matter.  Small straws have grown several inches during the last few months, but their life is very short.

It did not take us long to cover the first two kilometres, to where a forty metre wide stretch of gours and deep, rimstone pools almost blocks the passage.  The stream has maintained a low, aqueous route beneath the gours, while there is a more straight­forward, dry route over the top and through a low, oxbow lake on the uppermost rim-pool.  Without their monsoonal streams many of the caves in these tropical regions would soon be blocked with stal; long fossil systems seem to be rare here for this reason.  Should the Mae Lana stream change its course, then the cave would rapidly be blocked at these gours.

The gour-top lake is fed by a tributary via sumps two kilometres to the south.  Quite clearly the flow does not vary greatly according to the seasons, as the whole of the passage is richly decorated with pristine, white stal.  There are numerous pools up to neck deep with floors of thick mud, and lots of blind, white fish and crays live here.

Continuing downstream from the gours we soon came across rapids, and the roof lowered again.  The passage became narrower and the stream suddenly tumbled down a three metre waterfall and disappeared along a narrowing rift.  Up to our right large passage could be seen, and we climbed to a shelf and across boulders into the edge of a chamber three hundred and fifty metres long, and varying between forty and seventy metres high and wide.  Although this sounds vast it did not seem so at the time as the floor is composed of huge mounds of boulders, and we skirted the base of these.

Now that we had entered this dry sump-bypass of huge, old, abandoned passages and chambers route finding became a problem.  With no handy stream to follow and the possibility of a myriad hidden ways behind house-sized boulders our progress slowed dramatically.  We left frequent cairns in case we had to find our way back, and our compasses were in continual use, checking the trend of whichever wall we had decided to follow. Looking for routes onwards across sixty or seventy metres of passage takes time.  We had eventually climbed a crumbling, fault-shattered slope until, close to the roof, an almost imperceptible draught revealed a loose, descending traverse to a recognisable landmark - the Red Crystal Stream.  This is the only feature named on the survey, and is a relatively insignificant ochreous orange stal flow along the floor at the edge of the passage, but we now knew exactly where we were, at approximately the half way point through the cave.

The floor became sandy and the boulders less frequent, and then a short stretch of scalloped bedrock led down to water, with the stream resurging from among boulders on the opposite side of the passage.  Only a couple of hundred metres further on we left the stream once more, for a second sump-bypass.  The stream itself continues for five hundred metres in large, meandering passage to a deep, green-blue sump pool, and enters the main passage again further on.  We climbed a sandy bank to the edge of a well decorated series of dry galleries.  The first section contained some good, white flows, stalactites and thin curtains, well worth seeing after the comparative paucity of stal in the stream cave, but we were more fascinated by the next chamber.  The level, mud­brown, stal floor was littered with cave pearls, ranging in size from marbles to golf balls.  Each sat, free to rotate, in its own little calcite cup.  Taking care not to tread on any, which was not easy considering their profusion, we made our way on compass bearings to the base of an enormous pile of heavily stalagmited boulders.  Heading up these, occasionally following the faint marks of the original explorers, we were fortunate to find one area of constant drip, where we could replenish our water supplies.  We were drinking quite a lot, and maintaining a two to three inch flame on the carbides, which needed frequent topping up.

Ahead of us the cave opened up yet again as we entered the side of another big chamber.  Stalagmites more than ten metres high would have dominated most chambers, but here they were almost lost, tucked away near the bottom of a three hundred metre long slope, which rose through extensive rockfall for over one hundred metres to the right.  Our way lay down to the left where we dropped quickly to a level mud floor. After another brief route finding delay we climbed down more boulders to the sound of flowing water, and found the stream once more, moving sluggishly through muddy hollows among rocks.

We had been caving steadily now for six and a half hours, and it would be dark outside, so there seemed little point in pressing on yet.  On the descent to the stream we carne upon a sandy shelf in a little alcove of black, scalloped rock - ideal for a bivouac.  Wrapped up in a polythene sheet, we slept comfortably for four hours or so.

We awoke soon after midnight, had "breakfast", and set off downstream.  Thus far we had not had to swim, but we understood that there were numerous deep pools in this lower section of the cave and short swims would be necessary.  To begin with the passage was quite wide and about fifty metres high, but it rapidly narrowed to a few metres and varied from around ten to forty metres in height. The swims were in the narrowest parts of the passage, where it was just too wide for traversing and not wide enough for ledges as well as water, but each swim was only a few metres long. Jane, whose total confidence in water never ceases to amaze me, went first through the clear pools, treading carefully and finding all sorts of underwater projections and boulders. This procedure eliminated most of the swims, although we were still often wading in neck deep water.

The cave was all easy going in the streamway, with no route finding problems, and after two and a half hours we could smell the fresh air.  Leaves and earth had dropped down through crevices in the bouldery roof, and a long, straight, pipe-like root drank water from the stream bed.  We had made it after only nine hour's caving.

It was still dark outside, so we waited in the exit chamber until the bats, in their dozens, carne flocking past us to their roosts deeper in the cave.  We emerged to a pale, grey light which brightened quickly to a pink dawn while we climbed through the cliffs of the Nam Khong valley.  The raucous cries of hornbills disturbed the morning air as they flapped their ungainly way among the tree-tops, and we stood awhile to watch the early sun pick out the limestone towers and ridges, stretching away into the misty blueness of Burma.

Graham Wilton-Jones
9.7.1987 Kuwait