The island is about 55 x 19 miles (90 x 30 km) in extent, and encloses several lakes, particularly the 20-mile long Lake Rosa which occupies much of its western half.
The island is about 55 x 19 miles (90 x 30 km) in extent, the highest point being 132 ft (40 m) on East Hill. It encloses several lakes, most notably the 12-mile long Lake Rosa which occupies much of its western half.