Taal Lake is a freshwater lake in the province of Batangas, on the island of Luzon, Philippines. The lake is situated within a caldera formed by very large eruptions between 500,000 and 100,000 years ago. It is the country's third largest lake (the largest being Laguna de Bay). Volcano Island, the location of Taal Volcano's historical eruptions and responsible for the lake's sulfuric content, lies near the center of the lake. There is a crater lake on Volcano Island, which is in Lake Taal, which is located on Luzon Island. That crater lake is the world's largest lake on an island in a lake on an island, and it in turn contains its own small island, Vulcan Point.