From the same parking space as that of Los Morrillos Lighthouse, or from another further on down the track bending left from the lighthouse-approach track, you can follow the trails out to an immaculate crescent beach, where a protected bay makes excellent swimming for both humans and manatees. The beach here is touted as one of western Puerto Rico's best (and given even greater accolades by some): one thing it most certainly has is a welcome feeling of isolation.
Trails from here circle back up to the lighthouse, or you can continue exploring around the windswept headlands.