In winter also it sometimes entirely breaks up its covering of ice and gives off great clouds of steam.
Evidently the bottom of the lake is sporadically pierced by discharging hot springs or, perhaps, by streams of lava.

Evidence of some great underground convulsion like this is afforded by the mass of killed fish which at times dams the outlet river in its shallow places.

The lake is exceedingly rich in fish, chiefly varieties of trout and salmon, and is famous for its wonderful "white fish," which was previously sent all over Siberia and even down into Manchuria so far as Moukden.

It is fat and remarkably tender and produces fine caviar.

Another variety in the lake is the white khayrus or trout, which in the migration season, contrary to the customs of most fish, goes down stream into the Yaga, where it sometimes fills the river from bank to bank with swarms of backs breaking the surface of the water.