I too am on the Triumph in March for Canadian march break, March 15th. Perhaps we are on the same one!
It looks like we can leave the boat and walk around right by the Port and there is lots to see and safe. There is a lights and sound show in the old port I read about.http://www.puertoricodaytrips.com/lights-and-shadows/
However it seems a little expensive.
And this walking tour..http://www.puertoricodaytrips.com/ol...-walking-tour/
There is a roll call for the Carnival sailing on the Carnival Connections site if you are interested in getting to know a few people before you go!
Happy New Year!