Planning a trip to Borneo is a little like ordering a Harley-Davidson: a thrilling, nearly surreal thought, a pipedream, until the day the man knocks on your door. Your huge and dangerous machine is here -- care to take it out on the freeway?

So you get on the plane to Borneo, full of the unhelpful comments of your friends, the headhunter jokes and the odd bits of information about huge, wily pythons and foot-long leeches that stand up when they see you.

It's so far away and so strange that anything seems possible. My sister, horrified, said, "I looked at a map, Jimmy, and my God, it's beyond 'Nam." And at a party, a friend just got serious and said, "Nobody knows about Borneo."

Actually, you can't go to "Borneo" per se. Malaysia, Indonesia and Brunei hold pieces of the island, which is the world's third largest, behind Greenland and Papua New Guinea. The island is about as big as Texas, floating there in the South China Sea, southeast of Vietnam. The equator divides Borneo rather neatly in half, and the place contains some of the most ancient rain forest in the world, far older than the forests of the Amazon Basin. The interior of the island is mountainous and jungle-clad, and the tribal people there have had little contact with the outside world.

I had decided to go to East Malaysia, to the state of Sabah on the northern tip of the island, to see the rain forest and to fulfill an old quest -- to find the place in the world where I could see the widest range of climate and topography in the smallest space. Mount Kinabalu in Sabah is the highest peak in Southeast Asia: Its cold granite peak, at 13,455 feet, is less than 60 miles from the 80-degree water, the tropical islands and coral reefs offshore. It is a place to see all the world's riches at once.

And after all the superstition, Borneo turns out to be a surprise. One finds oneself in the Malaysian city of Kota Kinabalu, in a posh beach hotel that might be in Sarasota, Fla. On TV, the Los Angeles Lakers play the Phoenix Suns in last year's playoff game, from some station in L.A., complete with drawling American commentators. But just when you begin to forget entirely where you are, a picture of a mosque breaks into the action, and the wailing song of asr, the evening prayer.

Bombed flat by U.S. forces while it was held by the Japanese in World War II, Kota Kinabalu is new and modern, the strangeness and ancientness of Borneo pushed into the background. There is the silken atmosphere of the tropics, saturated and hot, and the usual afternoon downpour. And there is the jungle on the hills beyond town, the most ancient rain forest in the world, and over everything, the towering and weird peak of Mount Kinabalu, visible for hundreds of miles in its shroud of mist. For ages the people here looked up at the mountain, thinking of it as the last abode of the ancestors, the realm of the dead.

In the town below, the mountain is spoken of familiarly, as Kini or Nabalu, the words together meaning, according to one story, "Widow of the Chinaman," after a legendary abandoned bride, waiting on the peak for the return of her merchant husband. On the mountain, though, it is taboo to speak the name aloud. There the Kazadan, the hill people, refer to it as Agayoh Ngaran, "The Big Name."

Though not huge by Himalayan standards, the peak is surely one of the world's most impressive mountains. It is 10,000 feet higher than the surrounding ridges, and horned with a dozen pointed towers of granite. From the plane, I saw its anomalous crest breaking the cloud layer, like a big rock in rough surf.

The first English explorers of the region climbed Kinabalu in 1851, led by Kazadan guides who performed elaborate rituals, menghagi, to placate the disturbed souls of the ancestors. A white cockerel was killed, its tailfeathers planted in a row in the ground; long prayers were offered, in which the names of the offending white men were mentioned prominently; finally, on the granite face at the mountain's crown, guns were fired to warn the spirits. The guides still perform a version of this ceremony in an annual rite. But the custom now, among the young people of Sabah, is to witness the sunrise from the peak.

To do that, you must book a guide at the base camp of the mountain, then climb out of the steep jungle canyons for 7,000 feet, and sleep, sort of, in a hut just below the treeline. At 3 a.m. the guide awakens you in the darkness, and you proceed up the mountain by flashlight. With luck you reach the summit before dawn.

My guide Solimin was a small, strong Kazadan, in age somewhere between 35 and 60, who wore a round-brimmed denim hat, chewed betel nut and spoke no English, or very little. If I said "rest," he would wait patiently, indefatigably, a step or two behind me, chewing or smoking a strange stogie: a hollow stem filled with some fragrant herb and tied up with string. If we came to a fork in the trail, he would simply point.

The climb is hard, out of the rain forest, like ascending stairs for hundreds of stories. Despite the daily rainfall and the incursions of jungle, the trail is beautifully maintained, by hand, each step or handrail cut from the woods with the Kazadans' machete, called a parang. The trail switches back and forth over the razorbacked ridges, through the world's richest flora: 40 species of oak, 15 of flowering rhododendron, profusions of vine and bamboo, the whole thing steaming and flourishing, rife with birdsong.

For me, it was rather difficult to appreciate any of this on the way up. One may hire a porter -- I didn't and labored mightily beneath my backpack, seeing only the next step, and the next. It was hot and my clothes were soaked. I thought at first I'd climb for an hour without a break -- I made it for 45 minutes, and by the end I was resting every 10 or 12 steps, my heart thundering in my chest.

At 9,000 feet the terrain began to change drastically. Here an outcropping of alkaline rocks made for an orange, toxic soil, out of which struggled dwarf pine and grayish sayat-sayat with its white blossoms. Here I met an Englishman on his way down. He looked, in a word, awful -- grim and green -- and was of the ancient mariner sort, shaken and full of foreboding advice.

He'd climbed on, the day before, to 12,000 feet before making camp, and had accomplished that feat in the regular afternoon thunderstorm. He'd arrived, wet, at a hut above the treeline, where he'd spent a freezing night listening to some local rodents, the Kinabalu Rat no doubt, trying to climb the bunk bed posts. Worthy of Poe, this, I thought.

Worse yet was his predawn climb. The rain had continued into the night, and as he'd gone up the water was pouring in spates off the rock. You had to pull yourself up the granite by ropes, he'd found, and climb slippery wooden ladders. His hands had gone numb. You could get killed up there, he said.

I thanked him for his advice, and ever the chipper yank, said, "At least you'll have a story to tell." This appeared to cheer him not at all, and he continued his descent as my guide and I pressed on.

We reached the base camp hut about an hour later, just before it began to rain. The guide lit a fire and went to bed, falling asleep immediately in the middle of the afternoon. I stayed up, eating cookies and worrying.

I should have gone to bed. When the rain stopped, the clouds blew off the mountain, and suddenly above the hut there was an empire of granite, thousands of feet above, as awesome as El Capitan, thick rivulets of water running off the face in falls. Great, I thought. Now all I have to do is go up there in the middle of the night with a flashlight.

Later in the week I was supposed to go snorkeling at the other national park in the area, a group of offshore islands, where I had hoped to hover in warm water over the beautiful reefs of coral. Now I knew I'd never see any of that. I lay in my sleeping bag, hyperventilating in the thin air.

After a miserable while, I got up and did a strange thing. The hut, I knew, was near the traditional place of sacrifice, Panar Luban. Lacking a cockerel, I took an orange out of my backpack and found a flat rock, out of sight of the hut. I remembered the poet Gary Snyder saying that offerings to the gods multiplied considerably in the spirit world -- that a thimble of sake would be enough for a big party. I left six orange sections for the ancestors -- OJ for a month -- gazed at the peak a while and went to bed, suddenly calm.

The guide got up at 2 -- I heard him making his fire. I put on gloves and a wool hat and a down jacket, thankful I had been credulous enough to believe the guidebook that said I'd need them here at the equator. The guide led the way as we ascended in the dark, seeing only the circles of light our flashlights cast on the granite.

We passed other huts, where other climbers joined us on the steep rough-hewn stairs that the Englishman had told me about. A thousand feet higher, I looked back to see 40 or so flashlight beams bobbing and flashing as their owners negotiated the stairs.

The roped sections of the face were scrambles up a 40-degree slope, which eventually opened onto a wide sloping saddle, the summit plateau. Around us rose the strange rhino-horned peaks of the mountain, and above them the enormous pile of frost-shattered blocks that is Low's Peak, the summit of Kinabalu. Here other climbers were clambering along with their flashlights, speaking in a babble of tongues -- in Bahasa, Dutch, Japanese and a couple of kinds of English. The kids from the tropics didn't seem used to the cold, and were wearing all sorts of bizarre garb, like pink angora sweaters and outlandish hats.

Finally we reached the summit, all of us sitting down as we reached the top, like a nest of odd birds on the peak, the sky brightening, the black drop of Low's Gully falling away for a mile or so just a few steps to the east.

This morning the sun did not exactly appear. High clouds blocked the horizon to the east, and towers of fog drifted over the granite. Still the light came up over the stupendous rock, and there we were, colors and languages on the dark stone of the summit.

In an hour I had celebrated with chocolate and coffee and begun the painful descent, amazed, as the Englishman had said I would be, to see what I had traversed in the dark, and thankful that the orange sections had worked. I would live to snorkel.

The Tuanku Abdul Rahman National Park is Sabah's other great beauty and is mostly under water. It consists of five small islands and the surrounding seas, all in the South China Sea and just offshore of Kota Kinabalu, the state's capital. These are the perfect tropical islands, most of them small enough to walk around, accessible by launch from the mainland, and each encircled by extravagant coral reefs and whole cities of fish.

Legend has it that when the servants of the Sultan of Johore were delivering his daughter to her betrothed, the Prince of Sulu, a rival suitor, the Prince of Brunei, overtook the vessel on the high seas and absconded with her. She was partial to Brunei, anyway, the story goes. But the Johore sailors, having failed in their mission, had nowhere to go -- to return to Johore would be sure death. So they settled on the coastal islands along the northern shores of Borneo and called themselves the Bajau people. Or so the story goes.

The Bajau are still there, living on Pulau Gaya, largest of the islands in the park. They live in houses on stilts above the tide and ply the waters from Kota Kinabalu with their loads of tourists. The last Europeans to live on the island left rather abruptly in 1897 when Mat Salleh, an early anti-colonial revolutionary with a reputation of being invincible to bullets, landed on the island, took the principal settlement of the North Borneo Company and burned the place to the ground. Mat Salleh died six years later, holed up in the hills, of a bullet.

Today most of the islands are empty and peaceful. On Pulau Gaya, monkeys and wild pigs live in the jungle, and Police Beach, where the local constabulary once had its target practice, is now wholly in the hands of the visitors.

Still sore from the climb, I took the launch across the harbor. The water temperature was 79 degrees, the air temperature about 10 degrees warmer. Thunderheads rose from the ocean on the distant horizon, rain streaking beneath them, but even the rain was warm, as if it was all meant to be humane, even medicinal.

The underwater environment here turns out to be perfect for coral, which can't live if the water temperature falls below 68 degrees. One might be able to imagine coral as a mineral, or, with some effort of the imagination, as a plant, but in fact it is fauna, not flora, and gets my nomination for Animal Least Likely to Be Mistaken for a Human Being. If scientists found coral on Saturn, it would probably fail to fully impress us: It is simply so different from our notions of life that it might not register.

In the Malaysia region there are perhaps 200 species of coral, and in the waters off Pulau Manukan, I found whole realms of it -- a dozen species, each strikingly different, all stunningly weird: Staghorn, spiky and antlerish, bright green; purple Cabbage with its clamlike lips; Brain Coral, cerebellum of the sea; wedding cake tiers of Mushroom Coral, like apartment buildings of the distant future or deep past. In fact each coral is a colony of tiny cup-shaped animals, carnivorous, related to the jellyfish.

And as if this weren't enough, around and through this metropolis of coral swam a whole production number of bright fish, fish with lips and banners, fish with punk colors, fish with horizontal stripes, fish with vertical strips, one with iridescent blue eyes, one black and protective as a terrier, coming out of the reef to bark silently at me in the water, one special only in numbers, a hundred thousand or so small silver darts moving in unison through their curves of flight.

Between dives I rested on the beach, stretching my sore calves and looking across the water to Kota Kinabalu. In comparison to the strenuous and difficult visit to the mountain, this place was almost dreamlike. The warm water buoyed me up so that I had simply to hang there and breathe through the snorkel, watching the spectacle going on beneath. And on the sand I felt nearly dissolved, the moist air seeming not so different than the water. The island was small, manageable -- one might walk around it in an hour or less -- and there was wild food: fish, fruit of the coconut, screw pine, mangosteen. It was easy to imagine deciding to stay, even without sure death facing you back home in Johore.

But above everything here, over the calm coastal sea and the city, stood the granite crown of Mount Kinabalu, a reminder like my sore calves of the difficulty of things. And of the need for difficulty, I thought, northern in my bones. There is, I guess, the challenge of difficulty and the challenge of ease, and nowhere had I found these in closer proximity than in Sabah, on the island of Borneo.