Coast Guard Beach, Eastham, is part of the Cape Cod National Seashore, and the National Park Service offers ranger-guided programs -- such as hikes-- in the area.
The beach stretches for miles, has cliffs, dunes, good swimming in summer (refreshing temperatures!), body-surfing and boogie-boarding. In summer, local parking is closed and access is by a shuttle bus. (You may have to pay to park -- check TripAdvisor for visitor tips.)
And check the National Park Service site for details about Coast Guard Beach: good places to see seals winter, where to see shorebirds on tidal flats.
--continue to Top Beach #7, Waimanalo Bay State Park, Oahu, Hawaii..