"Like the Galapagos, Baikal is a closed ecosystem"

Past eight in the evening on the last day of August, after a ten-hour climb, we haul ourselves to the high rim of the Baikal Canyon. From where we stand, high plateaus, in hard, clear light, seem to stretch forever westward to the Urals. Facing east, my companion, the huge Siberian woodsman Semyon Ustinov, spreads his long arms. Far below, his beloved Baikal, the most ancient lake on earth, is shrouded in mist that drifts up the steep talus slope as if in search of us. The canyon rim on which we stand is a mile or more above the surface of the lake, whose greatest depth is 6,300 feet, or 1.2 miles, with an additional four miles of sediment above the bedrock. The great Baikal rift is seven times as deep as the Grand Canyon, by far the deepest land depression on the planet.