Cayo Costa State Park The best shelling beach in the U.S. is not Captiva or Sanibel, the twin islands just over the mainland from Ft. Myers. There's one much better, located two islands to the north of Sanibel as the seagull flies. Nine-mile-long Cayo Costa may lack a bridge and chic hotels, but this state-park isle makes up for it with a staggering array of hard-to-find seashells.
Caladesi Island State Park , Florida I Island is just north of Clearwater Beach. Take a private boat or the Caladesi Connection ferry to stroll the 3-mile beach, kayak its mangrove trails, or hike under live oaks.