One of my favorite hikes is the trail to Survivor beach in Aguadilla. The hike starts at the end of Surfer's Beach road access, where you will see a clearly defined path and small bridge. Just follow the trail and continue up over the mountain edge, with the ocean to your left. There is typically always a breeze, so pack a lunch and plan to hang out for the afternoon.
Survivor beach is at the very end of the trail, but you can pull over by the water at other points too, especially at some of the small caves if you need some shade and a sandy place to hang for a minute.