The excursion was a lot of fun. I went with my DS6 while my DW stayed on board. We did it through the ship and it cost $75 for me and $50 for my son. You get off the ship and go to the end of the pier, we were tendered right over since we docked in the harbor that morning. The boat ride to the submarine at Buck Island is about 15 mins or so with Punch and water and the guide is funny and informative. You then hook up with the sub and climb down into it. If anyone is a little worried about confined spaces they shouldn't do this. We went down to about 80 feet, there is a counter that shows you how deep you are. We saw barracuda, sharks, turtles, lobster, parts of a shipwreck and lots of fish. If you take pictures should try and take them out the windows on the opposite side from you otherwise they turn out all blue. This same company owns the ones in GC as posted above, but they also do the screamin' eagle boat rides at St. Thomas which my son wants us to try next time. I do not know what it would cost if you did it privately through them. On the way back they bus you to the central part of Charlotte Amelie if you want with the obligatory souvenier store stop. Let me know if you have any other questions.