In the heat and humidity of the equatorial night, Peggy and I lay naked, unable to touch. Outside our open hut, tree frogs piped incessantly while katydids sawed and cicadas buzzed, a cacophony pierced by the screeches and hoots from an inky blackness. We were careful not to press against the flimsy mesh of the tent-like mosquito net that protected us from Borneo’s biting insects and the diseases they might carry. The kids, now six and eight, slumbered under their own mosquito net in a bed next to ours.

We were in Bako National Park on Asia’s largest island. Bako was meant to be a warm-up for Gunung Palung National Park, or “GP,” where we planned to spend a month. GP is a roadless Indonesian wilderness of rainforests, mountains, swamps, and rivers. Its sole structures then were a small collection of tin-roofed open-air huts set deep in the jungle, reached only by dugout canoe. The primitive Cabang Panti (“Cha-bong Pon-tee”) Research Station served as base camp for the scientist or two working there at any given time. A network of trails and incredible wildlife, not yet discovered by National Geographic, provided a glimpse of tropical rainforest perhaps unmatched in the world. I had visited GP the year before and left a changed man.

“Indonesia is a lot more primitive than this,” I told Peggy. “Nobody speaks English. There’s malaria, dengue, hookworm. I’m not sure we should go, really. I’m worried about the kids.”

Peggy turned to me. “We’ve come this far. We’re close. Your pictures from last year make it look amazing. We can protect the kids. And you know where to go and how to get there. I think we should do it.”

TROPICAL RAINFORESTS IN Asia, Africa, and South America have long fascinated scientists and laymen alike with their stunning, overwhelming array of life. Straddling the equator, Borneo’s tropical rainforest supports a higher-order biodiversity than any other on Earth. As in the Amazon, there is a dizzying array of small and tiny fantastical creatures that fill every square inch of rich, green plant life. But Borneo’s rainforests are twice as tall as those in South America: Borneo’s dipterocarp trees grow as high as redwoods. The world’s largest flower, Rafflesia, three feet across and smelling of rotten meat, lives there, too. Lianas—woody vines as big around as pine trees—hang from buttressed trees. Gourd-shaped carnivorous pitcher plants called nepenthes grow in spectacular diversity, with some specializing in catching bird droppings, some trapping rats and frogs, and others, with a more prosaic diet, feeding simply on ants and flies.

Unlike South American jungles, where there are few large animals of any kind, Borneo has pygmy forest elephants, dwarf rhinos, even wild forest cattle called banteng, and like the Amazon, it has big cats and small. But while the New World tropics have only the familiar white-tailed deer, Borneo has five species, ranging from the rabbit-sized mouse deer to the elk-sized sambar. The strange, fanged muntjac deer even barks like a dog. Besides eight varieties of monkeys, there are primitive primates, too, including the fist-sized tarsier that snatches insects with its alien-looking hands and the nocturnal slow loris, a small bear-shaped fruit eater. Best known are Borneo’s lesser and greater apes: the acrobatic gibbon and the 150-pound orangutan. Less famous are its dozen kinds of “flying” squirrels, flying lemurs, flying lizards, flying frogs, and even flying snakes, all of which glide from tree to tree. These wonders and more live on an island half the size of Alaska. Visiting Borneo is like going to another planet.

My first trip followed an invitation from Tim Laman, then a graduate student at Harvard. We had met at an international canopy conference and with mutual interests in science, adventure, and documentary photography we hit it off immediately. A tall, mustachioed redhead, Tim studied strangler figs in Borneo’s forest canopy and when he suggested we climb strangler figs together at his research site in GP, I jumped at the chance. Tim faxed me directions from a faded Xerox copy. It took me ten days in December to get from Anchorage to Cabang Panti by way of a malarial village called Teluk Melano. From Melano, I hired two locals to paddle a dugout sampan canoe to meet Tim at GP. As two young canopy scientists at the beginning of our careers, we climbed trees, took photos, and recorded observations in the forests, mountains, and swamps. We woke every morning to the delightful whoops of serenading gibbon families. We watched orangutans hang upside down by their hand-like feet feeding for hours on wild durian, then we tried the delicious fruit ourselves. And of course, we picked hundreds of terrestrial leeches from our clothes and sometimes—plump with blood—from our skin. While a nuisance, those bloodsuckers didn’t deter us from going out day after day in search of wonders.

That trip and the time I spent with Tim provided the most dazzling tropical experience of my life. The entire forest was fruiting—hundreds of species of trees, lianas, and herbs—during an infrequent and irregular mast event, alive with more different kinds of vertebrates and invertebrates than I’d ever seen anywhere. A highlight was a night spent one hundred and eighty feet up in a fruiting dipterocarp, my hammock suspended over a crow’s-nest-like orchid epiphyte encircling the trunk and fully ten feet across with dozens of hand-sized blossoms pollinated by thumb-sized bumblebees. That night, dew fell but no rain. At dawn, the rising sun melted away diaphanous mist clinging to rainforest giants. Awakened by the lion-like roar of a big male orangutan, I knew that Peggy and the kids had to experience Borneo.

As expected, they found Borneo’s wildlife in Bako fascinating. A long-nosed proboscis monkey, the size and color of a small deer, picked leaves in the crown of an oak-like mangrove. Below him, a foot-long mudskipper crawled across the muck with a mouthful of water in its bulbous head as a sort of reverse scuba. Literally a fish out of water, the mudskipper pulled itself along using fins as legs, looking like a primitive Permian tetrapod. Back at our hut, an eight-foot serpentine dinosaur of a monitor lizard prowled the premises, its long blue forked tongue tasting the air just steps from the tables and chairs where we played Yahtzee after lunch during afternoon rains.

The kids dutifully recorded these wonders in their journals. Roman had started in Singapore, exclaiming that “Chewing gum is illeagal!” In Kuching, capital of Sarawak, Malaysia, he tasted durian and mangosteen, the king and queen of fruits in Alfred Russel Wallace’s The Malay Archipelago. He recounted his divergent reactions in tidy print:

I ate a mangosteen and tried something worse than brustle sprouts! The Durien! Yuck! The mangosteen looks like a giant crow berrie. You would have to sqwash it to opan up! It’s the best fruit I ever tasted. It tasted like orange or yellow starburst with a tang.

Besides novel tastes and sights, we caught and handled new fauna and flora. At the edge of a city park lawn, Jazzy spotted a lone draco in a tree. Like the anoles we knew from Puerto Rico, the draco (Latin for “dragon”) is an arboreal lizard that does push-ups and fans its colorful dewlap to challenge territorial rivals. But unlike anoles—and more like dragons—dracos have wings and can glide. Picking up a clod of dirt, I threw it at the brown lizard, knocking it to the park lawn.

I hurried over to pick up the dazed, uninjured animal. The four of us inspected a thin, delicate lizard whose back was the color and pattern of lichen-covered tree bark. He had a short nose and alert eyes that watched us calmly but warily. We gently unfolded his wings that stretched across six ribs on each side, finding bright blue and black patches on their undersides. Used for gliding, the fragile patagia were as wide as the lizard’s body was long, filling the space between his front and hind limbs. We all delighted in holding such an exotic and unlikely creature: a flying lizard.

As an experiment in animal behavior, we decided to watch him glide. I gently tossed the draco ten feet into the air. At the peak of the toss, the lizard opened his patagia and deftly glided to the lawn twenty feet away.

We all looked at each other. “Wow!” both kids called out as they ran over to the lizard waiting in the grass.

Roman picked him up and tossed him again. At apogee, the lizard spread his wings, coasting to the lawn like a paper airplane.

Roman laughed in delight and turned to me. He flashed his teeth in an excited smile: “Cool!”

“Oh, Dad,” Jazzy said, “that’s mean! Let him go.”

“Here, Jazzy, why don’t you let him go. You found him. Just toss him up and toward his tree so he can glide home.”