I never book through the cruise line. I have found over the years of cruising that you can book whatever you are interested in on shore, plus this way you don't have to pay the cruise lines commission. The only time I did book through the cruise line was in Alaska, because the shore tours fill up very fast and I didn't want to miss out on the helicopter ride up to the glacier!
I didn't mean I would rent through the cruise line. Heavens we always do excursions on our own. What I meant was, should we prebook through a car rental agency b/4 we leave or will there be rental agencies when we get off the ship. We haven't been to St Martin for 10 years and don't know what the new pier and the surrounding area is like.
My daughter was there last May. They rented a jeep when they got off of the ship and spent the day exploring the island on their own. Check out Dawn beach if you get a chance - they really loved it. I hope this helps!!