Las Golondrnas
Location: Manatí
Getting there: From San Juan, drive 45 minutes west to Manatí. Park on the left side of the road about here. This road can get full on weekends, so arrive early. There is an old man who for years has guarded the cars on this road that is prone to break-ins. He works for tips. Walk towards the sand at the end of the road. The hike is short and fun, but not an entirely obvious route. Stay right and navigate towards here with Google Maps, it should take about 10 min each way. Or, walk behind the houses and follow that trail to get to the cave or Boquillas Beach.
General Info: There is some hiking in the area, there is a lot of shells and coral on the beach, many hermit crabs all over the beach and the forested areas, and another cave (sort of) if you walk the length of the beach away from the cave with water. You can hike to Boquillas Beach, and continue walking down the beach. Before you get to Golondrinas Cave you will see an information plaque with an info graph of the trails in the area.
Heads up: There are multiple forks in the trail but from what I can tell they all pretty much head in the same direction.