beach walk

The act of moving your hand surreptitiously down a woman's (can be your own) body from the breasts to the pubis, then just slightly over enough to feel the 'lapping of the sea'

Girl: "What's your hand going south for Grant?"
Boy: "Oh, just a beach walk.."
OR
Girl: "I was in the shower and my hand was going for a beach walk. Before I realised... it jumped straight in the surf"