What is the proper noun for beach?

There isn't a single proper noun for "beach" in general. A proper noun would be the name of a specific beach, like:

* South Beach (Miami)

* Copacabana Beach (Rio de Janeiro)

* Waikiki Beach (Honolulu)

* Sunset Beach (California)

Do you have a particular beach in mind? If so, I can help you find the proper noun for it!