The next day I took Oscar and his brother Nick, 13, and flew to Pangkalan Bun. We were met by a chap from Wild Orangutan Tours who took us to our klotok "Spirit".
The eight-metre-long riverboat, is so named because of its engine sound: tok-tok-tok.
Spirit's owner, Julham, was also our guide. We had a cook, Juleha, captain, Aje, and an assistant called Aan. At one end of Spirit's top deck was a "bathroom" - a seatless toilet and a barrel of brown river-water to use to sluice the toilet. And to bathe in, if we were brave enough.
We tok-tokked across the wide Sungai Kumai,and nosed into the narrower waterway, Sungai Sekonyer, lined by nipa palms. The river's colour, Julham said, was caused by illegal gold mining upstream.
The 415,040-hectare Tanjung Puting National Park is home to about 4000 orangutans and was the first place in Indonesia to carry out orangutan rehabilitation, training orphaned or former captive orangutans to live in the wild.
Once found throughout Southeast Asia, orangutans now live only in Sumatra and Borneo.
Our first stop was at Tanjung Harapan, one of three orangutan feeding stations in the national park. Sweating like mammals with faulty glands, we hiked 1km through the forest. Rangers arrived with backpacks full of bananas and a huge container of milk, hooting an orangutan greeting as they approached. Soon, swinging on vines, a young male orangutan arrived. He was joined by a mother and her baby. They ate and drank quickly before swinging off back into the jungle.
We returned to our klotok and continued up-river. Juleha whipped up a tasty dinner of noodles, tempe, chicken and veges in her tiny kitchen on the lower deck.
As night fell, air-borne monsters from the insect world came to visit. We switched off the bug-magnet and crawled into our mozzie-net tent on the deck where we slept squished together on thin mattresses.
At dawn we awoke to the sounds of the rainforest. Birds whooping, insects buzzing and, sadly, a distant chainsaw that was "not in the national park" Julham assured us. It was a reminder that as the rainforest is chipped away, orangutans face extinction.
Alive and well, however, was 28-year-old Doyok, the orangutan king of the Pondok Tangui area. Orangutan means "person of the forest", and Doyok was just that. A gigantic, shaggy, burnt-orange forest person with a wistful face, it was as if he knew his existence was under threat. He swung through the trees and onto the feeding platform, first in line for bananas and milk.
We travelled further upstream, Aje steering our klotok into the even smaller river, the Sungai Sekonyer Kecil. Gone was the milkiness in the water. It was now
a clear black mirror to the trees above, impossible to see where the water ended and the foliage began.
Camp Leakey was the end of our upstream journey. We were greeted by gibbons, multi-coloured squirrels, countless butterflies and wild pigs but, disappointingly, no leeches, it being the boys' dream to acquire a decent leech scar on their equatorial travels. The king of the camp, 29-year-old Tom, and his queen, Siswi, arrived. We walked around them. They walked around us. This was no zoo. We were told not to make eye contact and to hide our drink bottles, orangutans being known to take the odd snack from a backpack.
From Camp Leakey, we travelled downstream out of the national park and said goodbye to our crew. At Pangkalan Bun, an email from our travel agent in Bali told us our flight to Surabaya had been cancelled. Only two airlines fly into Pangkalan Bun. Ours had cancelled all flights for days. The other was fully booked.
I was hot, tired and filthy. As the news of the cancelled flight sunk in, I didn't know what to do. But this was travel - we had to take the rough with the smooth.
Knowing chocolate would help, I went to a bakery and bought everything with the Indonesian word "coklat" on the packet. On the way back to our hotel, I met Rudy. He was the fourth travel agent I'd approached along our dusty road. He managed to book us the last three seats on a plane out of Sampit (five hours away by road) the next day.
Rudy felt he could give me his honest opinion of Westerners. "They are very good looking," he observed. "And is it true you can have sex without being married? All the time? With many people?" I steered the conversation back to travel before it went any further. To Rudy, we foreigners must seem like aliens.
We drove to Sampit through oil palm plantations. Indonesia has one of the world's highest deforestation rates, losing an estimated three million hectares of rainforest each year to oil palm plantations, illegal logging and mining, and forest fires. No wonder the orangutans are in trouble. I was glad we'd seen them.
Ann Huston paid her family's own way to Borneo.
Getting there: Fly to Pangkalan Bun from Jakarta or Surabaya.
How to see the orangutans: Make arrangements in Kumai or sign up with a tour company. We travelled in the rainforest with Wild Orangutan Tours www.wildorangutantours.com.
Best time to go: May-September, busiest times are July and August.
What it costs: A three-day, two-night klotok adventure with Wild Orangutan Tours cost about $900.
