The circular Lake Mainit steeps the municipalities of Mainit and Alegria between Surigao & Butuan. At a certain season, one can look up to the purplish blooms of water hyacinths & lilies. Its calm waters is a sanctuary of thousands of wild ducks.
Lake Mainit is the 4th largest lake in the Philippines, with a total inland water of 17,000 hectares and also the deepest lake in the Philippines, w/ a depth of 180 meters & an elevation of 37 ms above sea level. The unspoiled teardrop-shaped lake is one of the most natural ecosystems in the region that has unique & diverse potentials among the largest lakes in the country. It has the most fresh water surrounded by some cold and hot springs in its different tributaries. Lake Mainit is home to some rare and delicacy fresh water fishes such as eel, locally known as “casili” (Anguilla Sp.), mudfish or “hayuan” (Ophicephallus striatus), Gurami (Gourami Belontiidae) & the “bolinao” (Neosthethus thessa) which is referred as found nowhere else in the world and which are among the numerous other existing migratory fishes (Catadramous fishes) passing over Kalinaoan River.