Isla Mujeres or Riviera Maya?

These are two of the best beach destinations on the coast, and the difference lies in their shape. Isla Mujeres has one outstanding beach, Playa Norte, where the water is so shallow and sheltered you can wade far out, and the sun sets over the bay. The island's eastern shore is rock and surf.

The Riviera Maya has more than 100km of sand and far more choice: busy town beaches in Playa del Carmen, turtle bays at Akumal and Xpu-Ha, coves below the cliff-top ruins at Tulum and empty stretches towards Sian Ka'an. Sargassum seaweed can reach both, but on the Riviera it affects the public beaches over longer spells.

Both serve Yucatecan cooking. On the island it comes down to fish: tikin xic grilled whole, ceviche and tacos from family stalls around the market. It is fresh and good value but quickly feels repetitive.

The Riviera Maya has more range, from cochinita pibil and sopa de lima at taquerias in Tulum town to the wood-fired kitchens along Tulum's beach road. Its weak points are resort buffets and generic menus on the main streets, so it rewards people who walk a few blocks back from the sea.

Neither is a place for museums or historic towns, but the Riviera Maya has real Maya sites. Tulum's walled city above the sea and the tall pyramids of Coba, linked by raised jungle roads, can fill a day or two. Isla Mujeres has the small shrine to Ixchel at Punta Sur, the overgrown Hacienda Mundaca and underwater sculptures that you see by snorkelling. That is an afternoon's sightseeing, not a reason to come.

The Riviera Maya is far livelier at night. Playa del Carmen fills the streets around Calle 12 with clubs and rooftop bars until the small hours, and Tulum adds DJ nights in jungle clearings and beach clubs.

On Isla Mujeres an evening means sunset drinks at Playa Norte, then open-fronted bars and a little dancing in the pedestrian streets. It is barefoot and friendly. Anyone wanting more has to work around the last boat back from Cancun.

Both are flat, and most of what is worth seeing is underwater. The Riviera Maya has much more of it: thousands of cenotes over long cave systems, the reef walls off Cozumel, and the lagoons and mangroves of Sian Ka'an with dolphins and crocodiles.

Isla Mujeres has one draw the coast does not: from about June to September you can swim with whale sharks in open water. Add bird-watching on Isla Contoy and snorkelling at Manchones reef, but on land there is little beyond the clifftop walk at Punta Sur.

The Riviera Maya is the better base for outings. From Tulum, Chichen Itza and colonial Valladolid are about two hours inland, Ek Balam makes a quieter alternative, and the Cozumel ferry leaves from Playa del Carmen. Isla Mujeres itself is one of the Riviera's day trips, by boat from the northern end of the coast.

From the island, every trip starts with the ferry and a connection on the mainland. Cancun's Maya museum is easy, but the big inland sites mean long organised days, so most visitors go only once or not at all.

The Riviera Maya is built for family trips. It has resorts with kids' clubs, calm reef bays at Akumal and Puerto Morelos where children snorkel among turtles, and a string of eco-parks with underground rivers and zip lines. Hire cars or transfers are usually part of the plan.

Isla Mujeres works well for families with small children: Playa Norte is almost a giant paddling pool, the turtle sanctuary delights young children and a golf-cart tour of the island is an outing in itself. After a few days, though, there is little else to do.

Getting around is much simpler on the island. The ferry dock, the town and Playa Norte are all within a short walk of each other, a single road leads by golf cart or bicycle to Punta Sur, and Cancun is about twenty minutes across the water.

The Riviera Maya is easy to understand, since everything lies along one highway with buses and colectivo vans, but the distances are real. Coba and the cenote roads are much easier with a hire car, and Tulum's taxis are expensive for the short distances.

The Riviera Maya has the wider choice. Playa del Carmen's Quinta Avenida is a long pedestrian street with a couple of open-air malls, and Tulum's small boutiques sell linen, woven baskets and design pieces. The island has a few streets of stalls where you bargain for silver, Huichol beadwork and hammocks, which is fine for souvenirs. For anything more you go to Cancun.

Neither is cheap, but Isla Mujeres is a little gentler on the budget. Guesthouses in town, the market loncherías and the cheap ferry help, though whale shark trips and golf-cart hire add up.

On the Riviera Maya, Tulum's beach hotels and restaurants cost about as much as many European resorts. Money goes furthest a few blocks back from the sea in Playa del Carmen or Puerto Morelos, getting around by colectivo.

Neither place is for theatre or concerts. The Riviera Maya at least has staged shows: evening shows at the eco-parks with the Maya ball game, folk dance and mariachi, plus resort entertainment and Latin or reggae bands in bars. On Isla Mujeres, live music means a guitarist in a restaurant, and folk dancing appears only at local festivals.

The Riviera Maya has a real wellness scene, centred on Tulum's jungle yoga shalas, retreats and thatched spas. Large resorts further up the coast have hydrotherapy circuits, and temazcal ceremonies and cenote swims are on offer all along it.

Isla Mujeres relaxes you in a simpler way: slow days, hammocks, a massage on the sand and the quiet southern and eastern shores. Some places offer a temazcal, but stay away from the streets near the ferry in high season if you want quiet.