The cruise will be docked close enough that you can walk to Old San Juan. You should be able to easily come and go before the cruise leaves. I recommend visiting the fort at the top of the hill. It's a great view and has some neat history. I am cruising on the Destiny on Apr. 15, so we will cross paths. I am trying to find out if you can buy liquor at the pier in San Juan. Last time I was there cruising with Royal Caribbean we were able to load up and take it right to our cabin. Enjoy!