The (latitude 26.436394, longitude-82.105589) is a low-lying barrier island with an area of around 4,900 hectares that was developed by sediment accretion, producing linear dune systems with a range in height (between 0 and 3 m above sea level). The interior of the island's lower elevation is surrounded by natural sand dune ridges, creating freshwater wetland. The freshwater wetlands of Sanibel Island are protected from subterranean saltwater intrusion from salty aquifers beneath the island and the Gulf of Mexico by osmotic pressure brought on by seasonal rains and a thin clay laye. During the summer and fall wet season, when Sanibel receives 85% of its annual precipitation, these wetlands flood, and during the winter and early spring dry season, the water levels drop. Therefore, Sanibel's conservation lands (about 50% of the island's land area) are primarily restricted to the island's flood-prone interior of freshwater.
