No-one who suffers it can help seasickness, so it's unfair to disapprove - after all, the hero of the Battle of Trafalgar, Admiral Lord Nelson, was notoriously seasick. His sailors loved him, so they weren't bothered by it. Whether he was afraid of heights is unknown but he seems happy to continue to stand on top of his column in Trafalgar Square.

I have mentioned Illya's problem with seasickness in passing, and also his swimming ability which I find much more interesting. Likewise Napoleon and his boat, but that only because it appears so much in the fandom.