It occurred to him, as a bit of an unbidden flash, that they weren't entirely certain what was or wasn't in the water. They were sort of trapped on the island, after all.
"We don't know for sure that the water's safe," James mentioned. "Or at least, safe enough for people to spend the whole night there." Still, there had to be an answer. If they couldn't keep Remus hedged in on their own, that just meant confinement. It wasn't ideal, but it'd work for this month. Till they could figure out something else. And there certainly wasn't any reason to mope about it. Remus could get himself down without any help at all.
"What about the library?" he essentially blurted out after a few moments' silence. "We could barricade the doors. Give you some chew toys and some coconuts to chase around, and you could have yourself a grand old time."
And hey, Remus liked libraries something fierce. Who knew, maybe it'd have a very calming effect. Zen-like, maybe. Wouldn't that be a riot.