What's a wilderness without quicksand?
Varieties can be mud, and the dreaded (and worse) sand and water version.
But these rules, rather than having the movie 'sucking' quicksand of rapid death, have the more realistic, but more boring, option of allowing the victim to tread water in the mud/sand.
Sorry that's all for this post - real life really intervening on my AtoZ challenge - but not failed yet! Come on Sunday rest day.