The trip to St Croix is long and difficult. You can take the ferry from St Thomas, which is a long (two + hour) bumpy ride. The easiest way is to take the Seaplane. You can also fly charter or small plane to and from the airports.

Yes you will need a car to really enjoy St Croix. There are tourist Taxi's, but they will end up costing almost as much as a rental car without the flexibility that driving yourself offers.

Have fun...

And if you are thinking of taking the ferry, keep checking as there is some question about whether or not they'll be operating for much longer unless they obtain some sort of subsidy. For one day, seaplane is really the only way.

I live on STX and like it a lot, but I would discourage you from attempting this, especially by ferry. Even by plane, it's hardly worth the effort. If you come by seaplane, you are limited to traveling during daylight hours. If you try Cape Air, your total travel time will be close to 3 hours.

There is plenty to see on STJ and STT. Save STX for another, longer stay.

Thanks for the 411 guys!

If you do really want to go to STX for a day trip I suggest taking the seaplane over and then doing the jeep tours ( www.stxtantantours.com ). You can walk from the seaplane to where the jeep tour picks you up. They'll take you on a great tour around a good portion of STX, you'll get to see a lot and you won't have to worry about driving yourself around. I heard from someone else on this board who had taken my suggestion and did this and they said they had a wonderful time and it was a great way to see a lot for only a one day trip over to STX.