Swimming, snorkeling, paddleboarding, boating, jet-skiing, hanging out on the beach
The Arenamar Cafe serves food and drinks, including a great piña colada, in the building near the western side of the beach. There are bathrooms there as well.
White Caribbean sand
The water at Sun Bay can be gloriously clear, or somewhat milky if it has been stirred up by storms. It's always beautiful though.
This is a southside beach on Route 997, 1/4 mile east of the Green Store in Esperanza.
Sun Bay is a public park administered by the Puerto Rico Dept. of Natural Resources. It is a huge expanse of white sand in a large half moon shape. On the left side, it is a rocky shoreline. In the middle is a very long sandy stretch with a small section of rocks and tidal pools near the center. On the right side, there is a long sand bar out to Cayo de Tierra, a small island which is interesting in its own right.
There are some good spots scattered all along the beach with palm trees and other trees to provide shade.