Rafting the Tatshenshini - a river that most people struggle to pronounce let alone locate - throws up the challenge of savagely cold water and churning rapids - not to mention the grizzly bears and rutting moose. But the biggest danger by far is scenery fatigue - your senses become blunted by a relentlessly beautiful and dramatic landscape. Take a stash of digital memory cards. Take five, take 10 - it doesn't matter, you'll fill them all.

Carving through the largest protected biosphere on Earth - 10,389 square miles of Canadian and Alaskan wilderness - the river nuzzles the highest peaks on the continent, revealing sheer-sided valleys, hanging glaciers and finally a lake of blue icebergs before it pours into the Pacific.