After our explorations of the small but hurrying mountain rivers during the last few months we have forgotten the sheer size and power of the Yukon River. At its narrowest point it is probably 100 yards wide. Swirling, hissing, silty water, the colour of milky coffee hides various depths of two to twenty feet, and treed islands choke the river course, making it difficult to find the main channel. We have to watch the water constantly for signs of hidden sandbars and ‘dead men’ (uprooted trees stuck in the sandbars, lurking just below the surface waiting to snap the propeller or ram a hole in the bow.

An April wind is blowing from the Alaskan mountains, swaying the frozen spruce, dislodging the last clumps of stubborn winter snow from their drooping, north-facing boughs. It’s a warm wind and it fills the valley with life and movement. It awakens the squirrels to build nurseries, causes cow moose to drive off their yearling calves so they can concentrate on their unborn, restless and heavy in their wombs. It lifts courting raven to soar and tumble in the thin mountain air, and it brings the grizzly out after a long winter sleep. We’ve been awaiting its arrival like the dramatic entrance of the lead actor in a classic play.