Big Bend Seagrasses Aquatic Preserve was established in 1985 and it is Florida's largest aquatic preserve, protecting over 900,000 acres of submerged lands.

The Big Bend Seagrasses Aquatic Preserve consists mainly of a large, undeveloped expanse of submerged seagrasses and nearshore marshlands located along 150 miles of the northeast coast of the Gulf of Mexico where the Florida peninsula joins the panhandle. The preserve boundary encompasses all tidal lands, islands, seagrass beds, shallow banks, and submerged bottoms from the mean high water line extending 9 miles into the Gulf of Mexico. Landward, it includes all natural waterways tidally connected to the preserve to the extent of state jurisdiction or US 98.