"Okay." He managed a quick smile, thin and fleeting and nowhere near as reassuring as he was going for before he slid down from the shelf, bracing himself against it, "At least it's warm. Be right back." He had to dunk himself completely just to get enough leverage to make it to the stairs, let alone dragging himself up them when they were half-submerged as it was.
He actually made it all the way to the door, and had enough time to thump against it, "Jammed by something outside." If he was going to say anything else it was lost under the fresh rumble that preceded another wave. He didn't have enough time to get out of the stairwell before it hit, and as he'd predicted it dragged him under and down.