Our guide killed the engine on the longboat and placed a finger to his lips.

We drifted silently towards the towering canopy lining Borneo's Kinabatangan River. He pointed upwards. We were about to see proboscis monkeys for the first time, living proof that evolution doesn't always stick the landing.

The dawn mist was lifting off the water as the first rays of sunlight filtered through the jungle. Four fellow tourists with well-worn binocular straps around their necks wore the unmistakable expression of people about to tick off a long-awaited bucket-list moment.

Our guide leant forward and whispered.

"Just coming into view now..."

Camera shutters were poised. Nobody dared breathe.

Then, from somewhere near the middle of the boat:

"I'M BORED!"

My four-year-old absolutely nuked it.

A troop of giant cock-nosed primates vanished into the forest, leaving only swaying branches and four tourists staring at my wife and I with a look I still think about, two years later.

I'd love to tell you that was the last time one of my children declared they were bored in the middle of an extraordinary adventure.