Other than the town itself, the only thing in the area that constitutes a sight is El Fuerte de San Carlos de Boca Chica, the ruins of which are five minutes by motorboat from La Palma  on the island of Boca Chica. It should be easy to find a boatman willing to make the trip. Ask down by the boat ramps about el fuerte de Boca Chica. About US$10 for a small group should do it.
Note there’s a small battery on a neighboring islet, but the main fortifications are on Boca Chica. The Spanish built El Fuerte de San Carlos de Boca Chica in the mid-18th century as part of their network of defenses for the Espiritu Santo gold mines in Cana.
It’s not a big fort and the jungle has devoured much of it—a strangler fig has practically melded with what’s left. But it’s an impressive, photogenic sight, and it brings history vividly to life.
It doesn’t take much imagination to picture a poor, homesick Spanish soldier on lookout here, sweating in the jungle and keeping an eye out for pirates. The fort is a couple of minutes uphill from shore and so shrouded by forest it’s no longer easy to see from the water.
There are two Afro-Colonial towns a few minutes by boat from La Palma : Punta Alegre on the Golfo de San Miguel to the southwest and Chepigana near the mouth of the Río Tuira to the southeast, though they’re little more than collections of zinc-roofed shanties on the water’s edge.