I need some help?

While there are several cruise lines that leave from Miami and go San Juan, none are one way. Meaning you would have to pay for the entire one week cruise, even though you are only going to be on the ship for two nights.

I don't believe there are any cruises that to to San Juan from Tampa.

Also, your plan might be a violation of the Passenger Services Act (PSA) ...

No foreign vessels shall transport passengers between ports or places in the United States, either directly or by way of a foreign port, under a penalty of $300 for each passenger so transported and landed.

All the cruise ships in the Caribbean are foreign flagged ships. Puerto Rico is a US territory. Thus, if the cruise line allowed you to do what you are doing, it would be fined.

There are exceptions to the PSA, for example ...

In order to embark in a US port and disembark in a second US port, the vessel must visit either Aruba, Bonaire, Curacao or Colombia.

There are a few relocation cruises (meaning the cruise line is moving the ship from one home port to another) that result in a ship being relocated to San Juan. However, these are few and far between (perhaps one or two per year). Nonetheless, you would have to start in whatever US port the ship leaves from, visit either Aruba, Bonaire, Curacao or Colombia, and then finally end up in San Juan.

Now that I think of it, the Serenade of the Seas (Royal Caribbean) does this once per year at the end of the Alaska season (October of each year). The next one will be when the Serenade of the Seas leaves Los Angeles on October 26, 2008 and arrives in San Juan on November 8, 2008. The last port it visits before arriving in San Juan is in Aruba.

umm i think it would be possible i hope you have fun tho..lol

good luck