Cape Cod has over 40 ocean beaches that are also very enjoyable. There are too many to choose from. Some of the favorite Cape Cod beaches are Town Neck / Boardwalk Beach in Sandwich, Seagull Beach in West Yarmouth, Ballston Beach in Truro, Corporation Beach in Dennis, Sea Street Beach in Dennis Port, Marconi Beach in Wellfleet, and Coast Guard Beach in Eastham. Each one has its own personality and all of them are full of character and charm.
Take note, in the summer time Cape Cod is extremely busy, usually with a great mass of people and packed road ways that can be even worse than the chaotic and frustrating traffic in Boston MA and Los Angeles California combined. It can take 2 hours to travel 20 miles, painful. Things quiet down in mid September to mid October so if you can hold off until then, that is the time to enjoy Cape Cod. The other time to take advantage of a vacation on Cape Cod is in mid May to mid June before things really heat up and get going.
Yes another reason to take your summer beach vacation in Plymouth MA instead. Just so much less hassle and the beaches are as nice maybe even nicer (which is my thought) than the Cape Cod beaches.