The San Juan River is one of the main river systems in Metro Manila, Philippines, and is a major tributary of the Pasig River. It begins near La Mesa Dam as the San Francisco del Monte River, which officially takes the name San Juan River when it meets with Mariblo Creek in Quezon City. As the San Juan River, it passes through Quezon City, San Juan, the Manila district of Santa Mesa, and Mandaluyong.
Aside from the San Francisco del Monte River, the San Juan River has five creeks as its main tributaries (starting from its mouth going upstream):
Upstream from the confluence with the Mariblo, the river is known as the San Francisco del Monte River. This river in turn divides upstream into the Dario Creek and the Pasong Tamó River.
Culiát Creek, whose headwaters are within the UP Diliman campus, empties into the Pasong Tamó River.
Coordinates: 14°38′00″N 121°01′59″E / 14.6333°N 121.0330°E