Ambergris Caye or Cozumel?

Cozumel is the better island for swimming, though neither has the long sandy beaches the colour of the water suggests. On Ambergris Caye you mostly swim from the end of a wooden dock, because there is seagrass close to shore. The quieter sand north of San Pedro and the still lagoon water at Secret Beach are the best spots.

On Cozumel, the beach clubs south of San Miguel down to Palancar and Punta Sur have ladders into clear water with reef a few strokes out, so a beach day doubles as a snorkel. The west coast also stays largely free of the seaweed that can wash up on both islands' eastern shores in the warmer months.

Ambergris Caye eats a little better. Spiny lobster is on menus through much of the year, with Belizean stew chicken, rice and beans, and fry jacks at breakfast. Choices run from roadside taco stands to candlelit dining rooms in the northern resorts.

On Cozumel the good cooking is Yucatecan, such as cochinita pibil and panuchos, but you have to find it a few streets back from a waterfront that mostly serves Tex-Mex to cruise passengers. Neither island is worth choosing for the food alone.

Neither island is a place for sightseeing, but Cozumel gives you a little more to see. San Gervasio's small temples along shaded forest paths recall the island's past as a Maya pilgrimage site to the goddess Ixchel, and the island museum and the Punta Sur lighthouse fill another morning. On Ambergris Caye, culture means a stroll past San Pedro's painted wooden houses and a look at the low mounds of Marco Gonzalez.

Ambergris Caye has the livelier evenings. San Pedro's bars on the sand and over the water fill at sunset, a few dance spots keep going past midnight, and the weekly rituals at the beach bars become part of a stay.

Cozumel follows the divers' early rhythm. Its waterfront bars are busiest in the late afternoon while the ships are in, and quiet after that. Anyone wanting a late night has to take the ferry to the mainland.

Both islands are built around a reef, but Ambergris Caye offers more ways to enjoy the outdoors. Hol Chan and Shark Ray Alley are a short boat ride from town, and the atolls of Turneffe and Lighthouse Reef bring the Blue Hole within a day's diving. The mangrove flats on the lagoon side are known for bonefish, permit and tarpon, and Bacalar Chico has birdlife and wild shore.

Cozumel's strength is narrower but deep. Divers drift along the coral walls at Palancar, Santa Rosa and Columbia in very clear water. On land there is little beyond the lagoons and crocodiles at Punta Sur and a ride along the empty east coast.

The two are about even here, but the outings differ in kind. From Ambergris Caye the easy trip is a water taxi to sleepy Caye Caulker. Organised tours reach the Maya plazas of Altun Ha or take you up the New River through jungle to Lamanai.

From Cozumel, everything starts with the ferry to Playa del Carmen. From there you can reach the cliff-top ruins of Tulum, the cenotes and Coba, though the crossing and drive make for a long day. Chichen Itza is too far for a day trip from either island.

Cozumel is better set up for children. Its beach clubs have pools and loungers, Chankanaab has sea lions and a reef lagoon, and glass-bottom and semi-submarine boats let non-swimmers see the coral. In the evening there is a square full of playgrounds.

Ambergris Caye offers flat, warm water, English as the everyday language and golf carts that children enjoy. But there are no attractions made for children, and the dock swimming and seagrass suit toddlers less well. A resort pool in the north is the practical answer there.

Getting around is about equally easy on both, though the means differ. Ambergris Caye runs on golf carts, with water taxis along the lagoon to resorts strung out north of the river bridge. Reaching the island takes a short flight or a boat ride of about an hour and a half.

Cozumel has a single paved road looping around the island, fixed-fare taxis and rental cars or scooters for the empty east side, and the mainland is a short ferry ride away.

Cozumel has more to buy, though it is cruise-port shopping. The San Miguel waterfront has duty-free jewellers and stalls of hammocks, embroidered blouses and Mexican vanilla, and the sales pitch can be insistent on cruise days. Ambergris Caye's Front Street is a gentler browse for hot sauce, Belizean coffee and chocolate, and carved hardwood bowls.

Cozumel is clearly the cheaper island. Staying in San Miguel and eating at the market and among islanders keeps costs moderate, and only resorts and boat dives push the bill up.

On Ambergris Caye almost everything arrives by boat, so meals, drinks and groceries cost as much as in North America or more. Beachfront rooms in the winter season are expensive. Guesthouses and taco stands help, but not enough to make it a budget choice.

Neither island has a theatre or concert hall, and the little there is depends on the calendar. Cozumel's carnival before Lent is one of Mexico's oldest, with comparsa troupes parading through San Miguel. On Ambergris Caye the summer lobster festival brings a few days of street music, and Garifuna drumming and punta dancing turn up now and then.

The two are much alike: rest comes from the setting, and spas mostly belong to the resorts. On Ambergris Caye the quiet lies north of the river bridge, with yoga decks facing the reef and only the trade wind at night. Cozumel's calm is in the adults-only resorts on the southern strip and along the empty east coast, and a few places offer a traditional Maya temazcal sweat lodge.