When we woke up it was raining so we decided to stay in for a bit. By the time it stopped raining it was a bit too late in the day to do much.
Over our late breakfast, early lunch, we chatted about our options. Cat Ba was far more developed than we had thought and we weren't going to be able to see anything without going on a tour. None of tours looked all that great and it was way too cold for most of them. We ended up just booking a ticket to Hanoi and then a train ticket to Sapa for the next night.
We then spent the rest of the day wandering around the shoreline and taking pictures. It was pretty, but very cold and we didn't really have the right type of clothes for it.
For dinner we went to the same place we had lunch at and then played a few games on their foozball table before calling it a night.