On a day in May a softly curving Western river can be curiously unpredictable, full of hidden delights and contemptuously unforgiving of just one human mistake. Well was this known to the 1,600 boating buffs who drove across the Mormon desert country in southeastern Utah last weekend and unhitched their outboards on the verdant shores of the Green River for the second annual 196-mile Canyon Country Friendship Cruise. Into the water they went, dodging sandbars, winding past craggy red cliffs, through deep and colorfully named canyons—Moonshining, Hell Roaring, Upheaval.
A green boater has no business in these waters. But an...