It is called surf spray, by Bumble and Bumble. This spray is ocean water in a spray bottle. This texturizes, with a salt water grit feel. There are several ways you can use this. In long layered hair it creates movement and beach wave texture.
Husband and wife team Paul DeSomma and Marsha Blaker translate their oceanic inspirations directly into their collaborative glass sculptures, frozen glass waves caught mid-crash and appearing to spray surf from the contained vessels.
I have never heard of Sea Salt hair spray for "beachy waves". Gee, I usually can't wait to rinse my hair and body off after a dip in the ocean, or else I am sticky and chafing. 8 Easy Hair Product DIYs For The Shiniest Locks Of Your Life