I was thinking Dior vetiver
Good choice, or LesNez Turtle Vetiver Back. Back to my nose has a slightly vegital oceanic vibe, like an inlet marina. I really enjoy it. Another good one for the beach would be my usual suggestion of Tommy Bahama Set Sail St. Bart's.
I like the way it performs in the heat personally. What about CDG Vettiveru? I think that would be a wonderful beach scent and it's one of my personal favorites when it gets really hot.