Awesome man! How long are you there for?
Rent a golf cart to get around the island. Visit all the beaches! We brought our own equipment and never rented but there are loads of places near the ferry port.
If you are taking the ferry make sure you have your tickets pre-purchased; as they can sell out fast. If you are staying a while try to get over to Culebrita that has the best/pristine reef near puerto rico! Captain Dave has a charter that can take you over there.
Snorkeling
#6 Best Beach in the world - Flamenco Beach: The reef (Shark Cage) is all the way on the right side of the beach, very easy to access the reef, no waves. Some corals, good fish.
Tamarindo Beach - Great reef (lots of gorgonians, acros, lps) can be wavy, Turtles come out at 9-10am till about noon. Rockyish Beach.
Melones Beach - Best reef on the island! lots of acro, big gorgonians and sea fans, can be wavy, turtles, manta rays, some big fish! can be difficult access.
Zoni Beach - no reef but amazing beach and supreme privacy!
Food!
Dinghy Dock - eat/drink right on the water, see the huge tarpoons
Mamacitas - eat/drink right on the water, see the huge tarpoons
Krusty Krab - Best fish/seafood on the island