Las Baulas de Guanacaste Marine National Park (Spanish: Parque Nacional Marino Las Baulas de Guanacaste) is a National Park of Costa Rica and a Ramsar Site.

The park is managed by the Tempisque Conservation Area, and covers approximately a 167.3 square kilometres (64.6 sq mi) marine area of the Tamarindo Bay, next to the town of Tamarindo.

It supports the largest nesting colony of leatherback sea turtles on the Pacific coast of the Americas.

More than half the park is underwater and protected but still allows recreation, such as surfing.

The National Park covers four beaches (Carbón, Ventanas, Grande and Langosta), as well as the Tamarindo estuary and mangroves at the mouth of the Matapalo River and the San Francisco River Estuary.