I wouldn’t consider this as falling, but i get your point, i don’t see why sinking shouldn’t also be falling

I should have specified: at least you won’t die from the impact

The Mariana Trench seems to be deeper, 11000 m compared to 7000 m. But I’m not sure what’s the reference point on Mars for elevation. But at least can’t fall into the Mariana Trench

The only information we have about the pool is the that some adults where asked. We don’t know the exact questions and who those adults are. But considering the rather old population, I think the UK even older than the US, this could also reflect in the outcome. A person who is barely able to walk, probably won’t be able to fight even a rat.