Xel-Há

Xel-Há is built around a natural inlet where an underground river runs out into the Caribbean, and the mix of fresh and salt water keeps it full of fish. Snorkelling there is unlimited. The other big piece is the river: you start upstream and float back down through mangrove on an inner tube or with a snorkel, while your bag is driven back to the main area for you.

Between those come cenotes, a sheltered bay with hammocks, jungle trails, zip lines that drop you into the river, rocks to jump from, and a lighthouse 40 metres tall with a slide running from 30 metres up. Paid extras include walking on the seabed in a helmet (no swimming needed), a motorised snorkel scooter, a manatee and a stingray encounter, a bike-and-zip-line circuit and a spa. Dolphin swims are sold separately through Delphinus.

Entry comes in two main versions. All-inclusive covers the buffet and drinks; the Light ticket covers most activities and soft drinks only. Children under five go free. Buying well ahead is cheaper. It is a full day, it is closed on Tuesdays, and the walk upriver is long, so wear proper shoes.