On a snorkeling tour one time in the Caribbean one time. I started following some fish, which then lead to me following another one for a brief time, and then another. I glanced around me and suddenly, all I see is wide open ocean. To my left, to my right, nothing but water, some fish, and the plants growing up from the bottom. I'm starting to freak out. I'd lost track of time and the rest of our crew. I went to the surface and turned around 180. I didn't realize how far I'd swum or how much time I'd lost track of! I swam back to the group and found my son. About then, it felt like time to go. We started following a group but it was a different tour! Fortunately, we found our boat and climbed back on shortly before they were leaving for the next snorkeling spot. I love snorkeling and diving but I can easily see how people develop thalassophobia!