Tunasan River

The Tunasan River (Ilog ng Tunasan), also referred to as the Tunasan–Cuyab River, is a river system in the Philippines. This river begins at the border of San Pedro, Laguna and Dasmariñas, Cavite, and ends 9 km at the border of San Pedro and Muntinlupa. It is one of 21 major tributaries of Laguna de Bay.

The river system has six adjoining creeks:
 * There are two in San Pedro, Laguna and Dasmariñas, Cavite;
 * Three creeks join the system from the ponds of Hallow Ridge Filipinas Golf in San Pedro; and
 * The last one connects from the drainage system of RMT Complex in Muntinlupa.

The depth of the Tunasan currently varies from 2 to 0.25 m.

Both the river and barangay Tunasan got their names from a medicinal plant locally called tunas (Nymphaea nouchali), which was abundant on the Tunasan River and the shoreline of Laguna de Bay.

The Tunasan River received media attention in 1994 and 1995 due to a series of "fish kills" caused by the high Biochemical Oxygen Demand from decomposing water lilies, and by the profusion of residential wastes that find their way into the river during the rainy season.