If his shivering bones can manage it, Papyrus tries to take a picture of the awful room. A few pictures, in case they're too blurred from the way he's flinching away from looking at it. The better to have some evidence of what he's seen down here, and prove to McCree he really went swimming down here...

And, you know, to show to anyone else who might be interested in an existential terror room, or a strangely coral'd book.

At least now he knows waterproof books exist. That's a silver lining to look forward to as he starts swimming away from that and in search of another way up and out.