Lake Río Cuarto (Spanish: Laguna Río Cuarto), is a fresh water crater lake located in the northern highlands of Costa Rica.

It is the deepest natural lake in Costa Rica at 66-metre (217 ft).

[1] It is located in Río Cuarto canton, of Alajuela province.

The lake Río Cuarto is a maar lake located within a crater, it has an almost circular outline.

There is no secondary volcanic activity present.