(unseen servant has a range of 60', so Carradoc will have his boat row upstream, staying to the right)
The owl flies back into his cloak. The wizard opens his eyes. He advances along the corridor towards the door. He will examine the door, ready to work at the lock (or to Help someone else trying) if there's a lock.
This room evidently serves as a prison. A half-dozen straw pallets covered by threadbare blankets are spread out on the floor, and a cask of water leans against one wall. A dark, slit-like window looks out to the west.
Carradoc stays in the corridor. He's curious about what's in the barrel, but would not want to overturn it, lest prisoners go without something to drink. If any pay attention to him carefully, you'd see he is almost skittish.
Carradoc has been inside a cell before, and does not choose to do so again.
There's little of interest in the room, and no current occupants for the most part. The view overlooks the underground stream where you can see the boat passing by.