Agojo - 12/20/2015 6:17 AM 
If you can, take the short hop over to St. Croix, it is worth it! Dive with SCUBA in Christensted or N2TheBlue in Fredericksted. The island is surrounded by 13,000’ deep wall. Recommend Fredericksted hotel, few blocks from N2TheBlue. 5 boat trips (10dives) 2 days morning & afternoon with free tanks for night shore dive on the pier (50yards from dive shop) and 3rd day morning to round out 12 dives in 2 1/2 days.
Did a shore dive in San Juan 5 years ago, it was so so. Most diving was several hours from San Juan and I had limited time.