Cenote Azul Bacalar

A few minutes south of Bacalar town, the jungle opens onto a circle of blue so dark it reads as bottomless - and nearly is. Cenote Azul plunges some 90 metres straight down, one of the deepest open cenotes on the peninsula, separated from the Lagoon of Seven Colors by only a thin natural causeway: on one side the lagoon's pale turquoise shallows, on the other this indigo well. There is no beach and no shallow end - swimmers enter from wooden decks and ladders at the palapa restaurant on the rim and float immediately over the void, an inkwell sensation that divides visitors into the thrilled and the politely declining. Freedivers train in its depths; ordinary swimmers cross between deck and the far mangrove wall, watched by small fish at the sunlit margins. The restaurant serves the classic long Mexican lunch above the water, and late afternoons bring locals for the after-work plunge. As a contrast shot to the lagoon's shallows - the same aquifer wearing its two extremes - it is unbeatable.

The landscape

• The blue depth - 90 metres of water directly under the ladder.
• The rim decks - entries straight into the deep.
• The lagoon contrast - turquoise shallows across the causeway.
• The palapa restaurant - lunch suspended over the well.

When to go

Dry-season mornings for the calmest, clearest surface; late afternoon for the local swim hour. It pairs naturally with Los Rapidos down the same road.

Things to know

There is no shallow water anywhere - confident swimmers only, and vests for everyone else. Sunscreen rules apply as across the lagoon. Weekend lunch crowds own the decks by two.

Nearby

Bacalar's fort, docks and Los Rapidos channel complete the lagoon's southern circuit.