Seahorse Key is a 165 acre island located in Levy County and is part of the Cedar Keys National Wildlife Refuge.  It is a former dune and has a 52 foot elevation, which is atypical for the Cedar Keys area.  The island has a rich history, bears extensive shell deposits of aboriginal origin, and contains interesting archeological excavations. During the early American occupation of Florida, the Cedar Keys were occupied by Seminoles.  Seahorse Key was used as a supply depot and military hospital, as well as a detention center for captured Indians during the Indian Wars of the 1830s and 1840s.  The present lighthouse at Seahorse Key was built in 1854 when the town of Cedar Key was the depot for all trade and communication up and down the Suwannee River.  In 1862 Union forces from the U.S.S. Hatteras attacked the port and rail terminus at Cedar Key and destroyed all structures of military value at Seahorse Key.  The light station was discontinued as a navigational beacon in 1915.  It is now on the National Register of Historic Places and is used as a dormitory in connection with educational programs. 

In 1951 the University of Florida established a Marine Laboratory at Seahorse Key, which is leased for this purpose from the U.S. Department of Interior.  The location at Seahorse Key provides access to diverse habitats including extensive banks of marine grasses and algae, sandy beaches, mangroves, sand and mud flats, oyster bars, sponge-shell litter channels, turtle grass beds and salt marshes.  The hammocks on the island are important as protected nesting areas for as many as 54,000 birds including brown pelicans, ibis, egrets, cormorants, herons, spoonbill and osprey. A tremendous variety of animals inhabit the local marine and coastal habitats. Oysters, clams, shrimps, blue crabs, stone crabs, and several varieties of fish occur in commercial quantities.

Ten miles beyond Cedar Key are habitats supporting diverse forms of subtropical and tropical marine life.  Seahorse Key is a valuable location where scientists can study ecological organization under simplified conditions that are subjected to periodic change.  One such influence is the fresh water outflows from the Suwannee and Waccasassa Rivers.   The bird rookery provides a seasonal input of concentrated energy. The island supports a diverse growth of plants at the northern limit for a number of tropical species.