The island is long and thin, measuring 25 miles long and 5 miles across at its widest point, though much of it is less than half a mile across. Although resorts are being erected up and down the coast, its outer reaches are still practically uninhabited. The remote northern extremity abuts Mexican territory, and the Hispanic influence is evident in language, customs, food and fiestas.

A narrow channel splits Ambergris Caye in two segments, known as South Island and North Island. Most services and many hotels, as well as the airstrip, are within walking distance of each other in San Pedro's town center, on the South Island. Water taxis from Belize City and Caye Caulker dock on the reef side of the island right in San Pedro's center. Both the Thunderbolt boat service from Corozal and the Water Jets service from Chetumal dock on the lagoon side.

North of town a toll bridge crosses the channel (vehicles BZ$5). From here, a paved road runs north for almost four miles. Once the concrete stops, the road is suitable for 4WDs although if it's not too wet you can also pass in golf carts. According to locals it won't be long before the road is paved all the way to the southern edge of Bacalar Chico National Park (13 miles).

The northernmost section of the North Island constitutes Bacalar Chico National Park, and the surrounding waters form Bacalar Chico Marine Reserve. The western shore has mangroves and wildlife along much of its length.

Many hotels and resorts are strung out along the coast both north and south of town. Cycling is a very convenient way to get around. Otherwise, a regular water shuttle runs between Amigos Dock and the North Island resorts.