The harbour is what gives Playa San Juan its character. Fishing boats still go out in the early morning and bring back the catch around midday — tuna, vieja, sardines, sometimes barracuda. The pier and slipway are open to walk, and at midday you can watch the boats unload directly to the restaurants ranged along the quay.
The breakwater shelters the village's small beach to the north and creates the calm water that makes the harbour swimmable in good weather. A small boatyard at the back of the harbour services the local fleet. Dolphin and whale-watching boats also depart from here — the strait between Tenerife and La Gomera holds resident populations of pilot whales and bottlenose dolphins.