Sea refugees

Two friends went on a spring fishing trip. They did not expect that they would be disturbed by the loud splash of water on the opposite bank of the "tricky lake". It is called so because of the warm water even in winter frosts. After meeting a girl throwing a fresh-frozen capelin into a pond, they learn that the lake is an underground river that partially comes to the surface at this location. And the dolphins from the Black Sea, who fled from the sounds of enemy sonar in search of a safe body of water, are now here.