This upstairs seafood restaurant on the north end of downtown near Airport Blvd (between 10 and 12 on Calle 20) has great, fresh seafood. Their bacon-wrapped shrimp is yummy as is their baked fish stuffed with shellfish and their sopa de maricosas (fish stew) is also good. And some locals say they have the best ceviche on the island.
Quite popular with locals but hasn't yet gotten much publicity on the various tourist websites. Open for lunch only but a good lunch it will be. Closes around 7 PM.
Be aware there is a very steep staircase up to the restaurant entrance and the step down is uneven. Don't take your 80 year old maiden aunt to this place.