The Cuicocha Lake, a crater lake within the Cuicocha caldera contains four dacitic lava domes which form two steep forested islands: Yerovi, the smaller, and Teodoro Wolf, the larger. People are prohibited on both. The rim of the caldera is extremely steep — so steep, in fact, that the accumulation of sediment is insufficient for most hydrophyte vegetation. An older lava dome from the Pleistocene forms part of the eastern rim. The lake, which is 200 m (656 ft) deep at its deepest point, is highly alkaline and contains little life. It has no known outlet.