Ton Sai Waterfall itself is only a bright ornament on a far more impressive scene. A series of pools strung on strands of sparkling waterfall lead you ever higher into Khao Phra Thaeo National Park, one of the last remaining growths of virgin jungle on Phuket. The stream carves a natural clearing through the dense vegetation, opening it up to the light and making a path for the visitor.

All around you rises the jungle, some of the trees soaring to 50 or 60 metres, lofty pillars in a temple that practically compels the reverent contemplation of nature. Sunlight filters through the leafy canopy to dapple forest floor and waterfall; high in the trees overhead, there is an unidentified flash of colour, perhaps some sort of parakeet.

Butterflies drift and flutter everywhere in the clearing around a pool. It's almost odd to see them here, in their natural habitat, rather than framed and behind glass on Sukhumvit Road in Bangkok. Several big black and white beauties are performing an aerial circus over the pool at the foot of the falls. A gaudy orange specimen flexes its wings in the sun by the water's edge. A pair of tiny yellow butterflies dazzle where they stray into a shaft of sunlight. Vivid splashes of crimson in the surrounding gloom turn out to be enormous hibiscus blossoms. In the pond itself, little freshwater crabs clamber about the rocks.

The tropical evergreen forest is the richest ecosystem on Earth. Four distinct yet interdependent communities of both flora and fauna rise from the grasses and ferns of the forest floor to the relatively open shrubs and young trees to the continuous treetop canopy at 20-25 metres, and finally to the upper canopy, where isolated giants emerge from the dense cover to reach heights of 50-60 metres.

Enormous ferns and palms erupt in lacy exuberance around the bases of gigantic trees guyed by adventitious root systems. Clumps of bamboo and other grasses compete with shrubs for space and light, crowding in on each other, clambering over and climbing their neighbours, the slower-growing plants smothering under the faster. The larger trees are garlanded with creepers, decorated with orchids, draped with mosses and thick ropy vines. Everywhere there is the fecund odour of rotting vegetation, dead matter forming a thick spongy humus, the fertile ground of new growth.

Animal life also abounds, though it isn't so much in evidence. Exotic creatures such as the pangolin (Manis javanica) sleep hidden in their burrows during the day. This mammal sports overlapping scales of a hard fingernail-like tissue and a prehensile tail, and curls up into an armoured ball when threatened. It comes out to hunt ants and termites by night; employing its long, sticky tongue, a single pangolin can put away 75 million ants in a year.

Another nocturnal animal is the slow loris (Nycticebus coucang). Primates with great round winsome eyes and an unfortunately laid-back attitude to getting from A to B, they are already considered an endangered species, although they continue to be trapped for sale as pets. At dusk, you can sometimes see the Malayan flying lemur (Cynoce-phalus variegatus). In the daytime it sleeps high out of sight in the forest canopy; at night it glides from tree to tree foraging for fruit, birds, leaves, and flowers.

And there are lots of other animal species, including monkeys, though even the diurnal animals tend to be shy. And a species such as the white-handed gibbon, for just one example, has good reason to be shy, since it is also on the endangered species list, and humans are its deadliest natural enemy.

Locals still take guns into Khao Phra Thaeo Wildlife Park to shoot wild pigs, mouse deer, birds and monkeys, despite laws that say they cannot.

Rubber planters still encroach on land belonging to the park, though rubber planting has already helped to reduce the original forest cover of Phuket to those vestiges that remain today.

In the jungle there is a plant called the strangler fig, which can begin life as an epiphyte high in the canopy, only later extending roots to the ground. It binds onto a host tree, slowly and inexorably strangling it as it grows until, eventually, the parasite stands alone where the host once flourished. As opportunistic and all-smothering as tropical vegetation can be, however, it is no match for the fevered pace of commercial development. Modern civilization is now strangling the virgin forest preserves, strangler figs and all.

First there was agriculture —notably the rubber plantations, which in this century have progressively displaced the original forest cover until now all that is left are a few besieged patches. Of course, agriculture has at the same time brought much of benefit to the island. (Just as the parasitic strangler has always had its place within the forest ecology as an important food source for monkeys, apes, birds, and bats alike.) More recently, though, with soaring land values on Phuket beginning to make rubber a bad investment, unrestrained commercial tourism is threatening eventually to choke out both rubber and what remains of the forest. Tourism carried to these rapacious extremes would be a blight that threatened the strangler fig itself.

Ironically, then, one of the greatest values of Ton Sai Waterfall lies in its very power to lure tourists, to attract hikers and picnickers, people who wouldn't otherwise come into the forest, exposing them to the grandeur of unspoiled nature and, it is to be hoped, winning them over to the conservationist cause. Ideally, tourism and what's left of the natural environment on Phuket will still be able to coexist to their mutual benefit.

To get to Ton Sai Waterfall and Khao Phra Thaeo Wildlife Park from Phuket Town, take a taxi or a local bus to Thalang and then get a motorcycle taxi; or self drive (see map on p8)

The park is open seven days a week. Thais often come to picnic; foreigners more often come to walk the trails. During the week, especially in the rainy season (when the park is actually at its best), you can feel as though the forest is your own private preserve, unspoiled even by the presence of other tourists.

Guides are available for walks on the nature trails. One trail up the waterfall only extends about 500 metres; you can follow another for about eight kilometres through the forest. Those with an aversion to leeches might want to avoid the latter hike during the rainy season, though the trees are greener and the falls more spectacular in this period.

A restaurant with cheap and tasty Thai food offers a deck overlooking the largest of the ponds, near the foot of the falls.