Laguna de Bacalar

Laguna de Bacalar is a long, narrow body of fresh water in the south of Quintana Roo, running roughly north to south for some 55 to 60 kilometres and never much more than two kilometres wide. The town of Bacalar sits on its western shore about 40 kilometres north of Chetumal, and the lagoon is shared between the municipalities of Bacalar and Othón P. Blanco. On a peninsula where rain usually disappears straight into the limestone, it is one of the very few permanent surface lakes, fed mostly from below by underground rivers and cenotes and draining south through the Estero de Chac toward the Río Hondo and Chetumal Bay.

Its nickname, the lagoon of seven colours, comes from the way the water shifts from milky turquoise over the shallow white sand near shore to cobalt and almost black where the bottom drops into cenotes. Three of these open inside the lagoon itself: Cocalitos, Cenote Esmeralda and Cenote Negro, the last more than 90 metres deep. The shallows hold what is described as the largest freshwater stromatolite system in the world, rocky mounds built over thousands of years by microbial mats and among the oldest forms of life on Earth. The name Bacalar is usually traced to the Maya Bakhalal, 'surrounded by reeds', and in colonial times English pirates reached the town through the channels to the south, which is why the Spanish built the Fuerte de San Felipe above the shore.

The lagoon is also fragile. In June 2020 the rains of Tropical Storm Cristóbal washed soil, organic matter and farm runoff into it and much of the water turned brown; the colours returned only gradually and patchily, and heavy rains in 2022 clouded it again. Researchers point to deforestation, lost mangrove, sewage and the growth in tourism. Proposals to make it a federal protected area have not gone ahead, but navigation rules announced in 2025 divide the water into speed zones and treat Los Rápidos and the Canal de los Piratas as sensitive areas, and stepping on stromatolites is forbidden.

Most visitors see it from a boat: pontoon tours of two to three hours leave from the docks in town and stop at the cenotes, Isla de los Pájaros and the Canal de los Piratas, and sailing, kayak and paddleboard trips are popular for the calm early mornings. Swimming is easy from the town balneario, the many lakeside docks and spots like Cocalitos and Los Rápidos.