This is the main island of the San Andrés group, and the largest of the Department. It is located at . It measures in length with a width of and covers an area of . There is a tiny lagoon in the centre of the island called Big Pond. The principal town is San Andrés in the north of the island. Another town is San Luis on the east coast. "Cayo Johnny" (Johnny Caye) lies ENE of German Point (Punta Norte), the island's northern tip, and Haynes Cay about the same distance east of the island. Cotton Cay is less than south of San Andrés town, on the northeastern coast.