At the south end of Avenida del Sol Nuevo, follow the crossroad to the right, toward Los Ayala [1]. Just as the road reaches its summit, curving left around the Guayabitos [2] headland, notice a dirt road forking right, downhill. It continues through a cemetery to Playa los Muertos (Beach of the Dead), where the graves come right down to the beach.
Ghosts notwithstanding, this is a scenic little sandy cove. On fair days get your fill of safe swimming, sunning on the beach, or tide-pooling among the clustered oysters and mussels and the skittering crabs. (Recently, however, the owners of houses above the beach have placed a gate across the private entrance road to discourage cars. They cannot legally bar people from the beach, so even if you have to hire a launch to drop you off and pick you up there, Playa los Muertos is worth it.)
Links:
[1] http://www.moon.com/destinations/puerto-vallarta/the-nayarit-coast/rincon-de-guayabitos/beaches/playa-los-ayala
[2] http://www.moon.com/destinations/puerto-vallarta/the-nayarit-coast/rincon-de-guayabitos