The San Juan River (Spanish: Río San Juan) is a Colombian river that flows into the Pacific Ocean through the Chocó Department. It is approximately 380 kilometres (240 mi) and drains a watershed of 16,000 square kilometres (6,200 sq mi). The river drains into a large delta that covers nearly 300 square kilometres (120 sq mi). The average discharge of the Rio San Juan is 2,054.67 m³/s.

The river begins on Cerro Caramanta in the West Andes. The delta is due north of Bahía Málaga and Buenaventura.

The mouth of the river has extensive stands of mangroves, part of the Esmeraldas-Pacific Colombia mangroves ecoregion.^[1]

• List of rivers of Colombia
• Pacific Region, Colombia