margarethe does not like swimming, isn’t a fan of the ocean or large bodies of water, and doesn’t like going on ships, all extremely inconvenient preferences considering her place of birth, the necessities of travel in her time (no planes to get over oceans), the high likelihood that someone wanting to prank her would probably shove her in a pool, etc.
she can swim–canals were a feature of her life as a child and she spent a lot of time doing stuff she Really Wasn’t Supposed To Do so naturally she caused a lot of trouble around the water. by “swim” i mean she can doggy paddle, which is kind of the natural way for someone who was never taught to swim to teach themselves how to swim, and she can stay afloat pretty well; she just really dislikes it. she doesn’t like the feeling of being suspended in the water. she feels vulnerable while swimming and has a very pronounced fear of drowning. if she did swim, she would be torn between wanting to do it in a crowd so that someone could rescue her if she went under, versus not wanting anyone to “see her like that.”
similarly, she doesn’t get seasick and can deal pretty well while on ships; she just doesn’t like it. she hates the motion of ships. she feels very unsafe on them and is always scared she’s going to fall overboard, or that the ship’s going to sink, or some other disaster will occur. if she can afford privacy while traveling by ship, she will sequester herself in that private space and only come out once in a while. she dislikes being out on large bodies of water; it makes her feel very vulnerable. she feels like (and, to some extent, rightfully so) if something bad were to happen, no one would come to help, because there isn’t anyone around.
if she has to, she will pretend she likes to swim or sail–certainly if a Rich Ultrabillionaire wanted to take her out on his Fancy Yacht she’d be extremely gung-ho about it (that kind of leisure activity is a kind of class marker), but she would be extremely anxious (and hiding it) the whole time. if invited to go swimming (by the same Rich Ultrabillionaire?) she’d do it, but she probably wouldn’t actually go into the water unless pressured, and even in modern verse, where revealing bathing suits are culturally acceptable, she would generally be covered head to toe. she does not find it soothing or relaxing to be beachside or poolside and have a lot of skin exposed, not least because she’s so pale.