Don Pedro Island State Park, FL
Credit: David Nevala / Getty Images

Accessible only by boat, Don Pedro is worth it for the "miles and miles of beaches," Leatherman says. This Gulf Coast island in Charlotte County, Florida, is a great place to collect shells. The water is warm and clean, and crowds are never an issue. "Most people don't know about it," Leatherman says. "It's a very underutilized beach."