Quintana Roo is where most visitors to Mexico land, and a great many never leave it. The state runs down the Caribbean side of the Yucatán peninsula from Cancún to the Belize border, and it holds the country's warmest sea, its second reef, and almost all of its all-inclusive hotels.
The coast divides sharply. Cancún is a planned resort city, built from nothing on a sandbar in the 1970s, and it works exactly as intended. Playa del Carmen is denser and more walkable; Tulum has the cliff-top ruins and a beach road of expensive hotels behind it. The islands are calmer — Isla Mujeres for a day, Cozumel for the diving, Holbox for sand streets and whale sharks in summer.
Behind the beach the limestone is riddled with cenotes — collapsed sinkholes into the freshwater table — which give this coast the best cavern diving and snorkelling in the Americas.
South of Tulum the development thins out fast. The Sian Ka'an biosphere reserve blocks the coast road, and beyond it Mahahual, Xcalak and Bacalar — the last on a lagoon of improbable blues — are what the Riviera Maya looked like thirty years ago. Chetumal on the border is a working city with an excellent Maya museum and no tourism to speak of.
