While in the I jumped on top of the bookshelf at the bottom of the stairs next to the table with the map on it and got stuck in the space between the bookshelf and the wall. Jumping until I got up and out, I ended up in an invisible floating pond and started swimming in the air.

It's also possible to fall through the floor by glitching into baskets and ending up back in the old ice caves below. This also happened to me inside the Wreck of the Brinehammer and there was no way to get back out.

Both glitches were easily repeatable.

whoops, thought that said dawnguard at first, was confused for a bit, I'll try to mimic it later to see if I get the same issue