Bacalar Lagoon

Bacalar earns its name honestly: the Lagoon of Seven Colors stretches some 40 kilometres over white limestone, and depth changes paint it in simultaneous bands - pale jade shallows, turquoise shelves, ink-blue holes where cenotes open in the lagoon floor. This is fresh water, not sea, which keeps it glass-clear and famously swimmable from the wooden docks that comb the town's shoreline. Its strangest treasure is alive: colonies of stromatolites, layered microbial reefs of a lineage stretching back billions of years, still growing in the shallows at spots like Los Rapidos - among the more significant freshwater formations anywhere. On the shore, the Fort of San Felipe, built in 1729 against Caribbean pirate raids, keeps its cannon and a small museum above the water. Sailboats, kayaks and pontoon tours work the lagoon at an unhurried, low-rise pace that still feels far from the Riviera.

What you actually see

• The colour bands - jade, turquoise and ink blue in one view.
• The stromatolites - living reef mounds from life's oldest lineage.
• The cenotes - deep blue wells opening in the lagoon floor.
• Fort San Felipe - the 1729 star fort and its lagoon-facing cannon.

When to go

November to May for dry, sunny days when the colours perform at full strength; midday light is peak blue. Summer brings heat, rain and the fullest lagoon.

Honest expectations

The rules matter: no sunscreen in the water and never touch or stand on the stromatolites - they grow over centuries and break in a second. Docks and tours cluster around town, so holiday weekends get busy even here. There is no beach as such - swimming is from docks and shallows.

Nearby

Chetumal's museums, the Kohunlich ruins and the long road north to Tulum.