It wasn't the first time he'd wished there was a window in the door. In fact, if he thought about it, which he really didn't have time to, it might have been closer to his five hundredth musing on doors and windows and the advantages of seeing what was on the other side before you flung it open willy-nilly. But he didn't have time to think about that. He only had time to think about who was knocking on the door, as the Tardis was currently nestled several fathoms below normal oceanic habitation. But still… he could've used the window.