I think you are referring to Mar de Tumbo Beach on which you will find Mata Rocks, Banana Beach, Tropica Beach, and Banyan Bay.
It's a long stretch of nearly white sand that is regularly raked in the hotel areas and is about 1� miles south of the centre of San Pedro town.
Banana Beach has a seawall that protects the hotel and keeps the beach area level directly in front of it, but you can easily enter the water from either side and the swimming is fairly good.
Enjoy,
Jim