Lake Sampaloc is an inactive volcanic maar on the island of Luzon, the Philippines.
It is the largest of the Seven Lakes of San Pablo, Laguna. Nearly half of the lake's depth has a shallow depression at the lake's bottom, indicating its volcanic origin. The lake is located behind San Pablo city hall and is dotted with fishpens and small cottages built on stilts.
A giant Sampaloc (Tamarindus indica or tamarind tree) once grew in the garden of a selfish, stingy old woman. One day, an old man begged for some tamarind fruit as a cure for his ailing grandson, but instead of helping him, the stingy old woman set her ferocious dogs upon him to drive him away. The old man was badly hurt, and was in fact a Diwata (local nymph or fairy) in disguise. After the Diwata (still appearing as the old man) had departed, there was a thundering noise and rain, followed by the cracking of the earth. The entire orchard sank into a colossal pit which was immediately filled with water, which villagers thence named after the large tamarind tree.