When I was young I wanted to sail around the world. I had friends in St Thomas living on a big sail boat. I packed my sail bag and headed down there. It was meant to charter but the owner was too drunk to organize anything, so we were able to spend some months on board sailing around the Virgin Islands. At the time, It was easy for me to get work cooking on boats and I had a job lined up on a boat going to Tahiti.
However, we finally left the shelter of the Virgins and went to St Barts. I woke in the night with water pouring into my mouth - we hit rough seas and my port hole was cracked open. I felt as sick as I have ever felt in my life. I was sea sick for three days non -stop. I couldn't move from the back of the boat, rain, shine, night, day, I laid at the stern heaving.
That did it - St Barts was lovely, and we next went to St Martain - but instead of sailing back to St Thomas I caught a plane home. I will never go through that again.
Take Dramamine BEFORE you leave - if you are already sick it will not work!