Achong is struggling to push our longboat against the current of Borneo's Batang Ai River, so we jump into the water to help him.
"Stay in the boat," he pleads, but we ignore him.
It's dry season and every ounce of weight is a factor as the longboat's hull scrapes the bottom of the shallow waterway.
This is the only time we ignore Achong.
Like other tattoo-covered Iban tribesman, he's a master boatman and this is his territory.
The Iban, once fearsome headhunters, are also expert trackers who have turned their talents to trailing one of the world's most fascinating endangered creatures: orangutans.
The ape pursuit takes us to Sri Aman Division, a remote area of Sarawak that nudges the border of Kalimantan, the Indonesian portion of Borneo.
Borneo and neighboring Sumatra island are the only places the shaggy-haired red ape survives.
The chances of seeing them in the wild are increasingly slim.
"There's no guarantee," warns Borneo Adventure in its publicity blurb for the Red Ape Trail, the safari that has brought us deep into the Asian island's dense, steamy jungle.
"Ape numbers are about 20,000 and constantly declining due to forestry, palm oil crops and poaching."
Far more certain is searing heat, humidity of 80-100%, slippery conditions and the possibility of leeches.
"This walk demands a great deal of physical and mental exertion," says Philip Yong, Borneo Adventure's co-founder. "The region is totally isolated from the outside world."
Fortunately there's a soft option -- surprisingly, it involves a longhouse.
Longhouses are the large jungle huts that generations of Iban and other Dayak tribes have called home.
Usually built on stilts, they're dark, communal living spaces often shared by several families.
The Hilton Batang Ai Longhouse Resort in the Sarawak region of Malaysia's portion of Borneo island takes its inspiration from traditional local homes, and translates this into luxury accommodation.
Seen from its jetty on the Batang Ai, a massive man-made reservoir in the Sri Aman region, the Hilton-managed resort appears like any other longhouse in the area.
Continue reading (Incl. Pics & Vids) at: CNN: On the trail of orangutans in Malaysia.