Cozumel — boat trip and El Cielo snorkelling

El Cielo, 'the sky' in Spanish, lies off south-west Cozumel, in a shallow, sandy zone: three to four metres of turquoise water over a white sandy bottom. What makes it special is a remarkable colony of starfish, which you can watch at fin level without diving. The boat takes in three reefs, Colombia, Palancar and Cielo, then the natural pool at Cielito.

One thing to plan for: as with every trip out of Cozumel, neither the ferry nor the journey to the pier is included in the price. You make your own way to the Playa del Carmen pier, buy your return ferry ticket, around 650 pesos or roughly thirty euros, and the team picks you up as you step off on the island. Lunch is also at your own expense. Out at sea, the guides stress the essential rule: never lift a starfish out of the water, even for a few seconds, or you risk causing irreversible harm. The activity must be paid in full the day before at the latest and is not open to under-fives.