The fee is to use the facilities as well as the beach. As stoners6 notes, there's a very long public beach north of Cosmo's.

I've been hanging out at Cosmo's since first trip in 1984. There isn't anything on the menu that isn't as good as it gets in simple Jamaican specialties. I love the steam or fried fish and bammy, curry conch, conch bits and chips, curry goat, stew peas, Oxtail and all the soups are great. Last winter, we met friends at a swanky restaurant and the food can't hold a candle to Cosmo's. Thank you, Cosmo Brown!