Abstract <p>The water balance is considered for the summit crater lakes on the Vernadsky Range, Paramushir Island. The input was based on precipitation at the crater heights. The necessary condition for the existence of permanent cold crater lakes with a precipitation of ∼4660 mm per hydrologic year is a drainage area exceeding 60 thousand m². The evolution of the lakes lying in the craters of the active Ebeko Volcano is discussed. An estimate is provided for volcanic input (inflow of water and/or vapor of volcanic origin) into thermal lakes during the preceding time periods and during the present-day condition of the volcano. The Middle Crater and the Korbut Crater are suitable for the formation of hot lakes. The formation of a lake in the Korbut Crater is impossible until the eruption in the crater has come to an end. A volcanic input of 8–13 kg/s will be sufficient for an equilibrium existence of a lake with temperature 35°С and water area 25 thousand m², assuming a crater diameter of 250 ± 50 m during the post-eruption period. The supply of volcanic vapor into Lake Goryachee in the Middle Crater has been recorded since 2017, but the lake remains cold. The volcanic input must be 5 ± 2 kg/s in order to achieve a balance equilibrium for a lake with temperature 35°С and water area 25 thousand m².</p>