I had known beforehand that I was prone to seasickness, so I brought seasick pills with me, set a repeating six-hour timer on my watch, and took a couple of pills every time my watch beeped, including in the middle of the night. This kept me feeling reasonably well.
In the afternoon, I suggested playing The Settlers of Catan, a German board game about settling an uninhabited island. It involves collecting and trading resources to build. I had brought the game with me, and I taught Anneka, Possum, and Dennis how to play. About 15 minutes into the game, the boat swayed a bit too much, and all the pieces ended up on the floor.
The rest of the day was uneventful.