It is a personal decision for sure. But, I will give you my two cents. In 30 plus years of visits to St. Barth, we only took the ferry once---had to as we missed the last plane out of SXM. Never again! We did not get sick but people all around us did. It was dreadful. Follow Missy's advice and ease your anxiety by taking a pill. And also, as has been noted, focus of taking pictures from the plane. The flight will be over before you know it! The exhilaration of coming down the stairs and putting your feet on the tarmac, anticipating your wonderful vacation, will make you realize flying is the way to go.