The sand here is as dark as it comes but it is soft and the 260-metre beach is rarely crowded. When it's calm, this is a lovely local beach.
On rough, windy days, you need to tuck up at the north end to avoid the blowing sand. Don't swim if nobody else is. Instead, walk south along the promenade until you reach a turnoff that heads down to the famous La Garita blow hole. This natural arch and deep pool rises and falls with the waves like the heartbeat of the ocean. Look out for lizards on the rocks by the promenade. Walk from La Garita south all the way to Playa del Hombre beach.
For food at La Garita beach, just grab a table at any of the restaurants clustered behind the sand at the north end. If they are all full, there's a Chinese restaurant up the steps behind the tree (but it closes in the afternoon).
La Garita has portacabin toilets just behind the sand, but they are only open when the lifeguard is on duty in the afternoons. Otherwise use the toilets in the restaurants at the north end of the beach (but wash your feet first).