Playa Grande
Playa Grande is on the Pacific coast of Costa Rica, far up on the northen end in Guanacaste Province. It is most famous as a home to Leatherback Sea Turtles which use the beach as a nesting ground.
The surf here is both active and steady. For surfers and body surfers this is one of the best spots in the country. A little further north up the beach the ocean may be calmer, so if being pounded by waves doesn't sound like an ideal day, it may be best to head up that direction.
This beach is somewhat difficult to get to, as there are no roads leading to it and no parking lots nearby. It also means it will probably be less crowded than other beaches around the area.
There is one resort flanking the beach, the Hotel Las Tortugas, which does offer rentals for some equipment like kayaks, snorkels, and surf boards.