Unlike the rest of the Keys, Key West actually has a few small beaches, although they don't compare with the state's wide natural wonders up the coast; the Keys' beaches are typically narrow and rocky. Here are your options: Smathers Beach, off South Roosevelt Boulevard west of the airport; Higgs Beach, along Atlantic Boulevard between White Street and Reynolds Road; and Fort Zachary Beach, located off the western end of Southard Boulevard.
A magnet for partying teenagers, Smathers Beach is Key West's largest and most overpopulated. Despite the number of rowdy teens, the beach is actually quite clean and looks lovely since its renovation in the spring of 2000. If you go early enough in the morning, you may notice people sleeping on the beach from the night before.
Higgs Beach is a favorite among Key West's gay crowds, but what many people don't know is that beneath the sand is an unmarked cemetery of African slaves who died while waiting for freedom. Higgs has a playground and tennis courts and is near the minute Rest Beach, which is actually hidden by the White Street Pier.
Although there is an entrance fee ($3.75 per car, plus more for each passenger), I recommend Fort Zachary Beach, since it includes a great historic fort, a Civil War museum, and a large picnic area with tables, barbecue grills, restrooms, and showers. Large trees scattered across 87 acres provide shade for those who are reluctant to bake in the sun. Hurricane George damaged the vulnerable point in 1998, but replanting of native vegetation has made it even better than before.