If you are going to be near Fajardo, I highly recommend SeaVentures (link Scuba Diving Puerto Rico's Caribbean with Sea Ventures Dive Centers - Fajardo & Palmas del Mar in Humacao, Puerto Rico). They are a fantastic shop. The underwater visibility there varies based on the conditions. If you go to Culebra or Vieques you will have better viz but it is more of a hassle to get to. There are other options on the west and south if they can make it to those parts of the island.