Wtih the Gulf of Mexico in the back ground, bring the waves into the beach. You can set under a plam umbrella. Longboat Key is a town in Manatee and Sarasota counties along the central west coast of the U.S. state of Florida, located on a barrier island of the same name. Longboat Key is south of Anna Maria Island, between Sarasota Bay and the Gulf of Mexico. It is almost equally divided between Manatee and Sarasota counties. The Town of Longboat Key was incorporated in 1955 and is part of the Bradenton–Sarasota–Venice Metropolitan Statistical Area.