I just don't understand how it could occur to no one in a group of three or four people for a whole hour. Like, even if the barrier had been fully built and worked perfectly even after considering the tide, they would have been making camp on fully soaked ground. Just what everyone wants first thing in the morning: to trudge through mud.

I think it did occur to everyone and that's part of the conclusion of the story - instead of stubbornly battling the situation we should brace it and adapt to it.