A phenomenon of ice rings in Lake Baikal is considered. A hydrodynamic theory is proposed according to which geostrophic vortices form under ice in the area near the ice rings. These vortices are due to bed relief, namely, underwater canyons; therefore, they are referred to as canyon vortices. It is shown that a divergent ring vortex forms under ice in the ring domain at the crossing of a vertical cylindrical Stewartson layer on the lateral surface of the canyon geostrophic vortex and under-ice horizontal Ekman layer in the form of a horizontal vortex torus, and the melting of ice below in the form of a ring is due to the formation of this vortex torus.