Nothing worse than sea sickness...
going back a few years now, we hit a group of atols and islands about 100nm off the northwest coast and out of 8 people, 3 of them were sick EVERY day.
Painful to watch and several of them havent hit the water again.
Then there was the time during an offshore navigation exercise when one of the other students was sick on the jetty before boarding.
AFAIK to this day, hes never stepped foot on a boat!