What the heck is this 'natural trampoline'?S

Check out what a pair of hikers discovered in a forest near a little river in St. Jerome, Quebec, Canada. It almost looks like someone buried a trampoline under a layer of topsoil, but what you're seeing is completely natural — and probably not very safe.

So what could have caused such a thing?

According to the video's creator, the vegetation on the ground is still living, and the bouncy sheet of soil and plants was strong enough to hold "many people."

I used to do landscaping when I was in university, so I recognize the sponginess as a potential sign of sphagnum, or peat moss. But it seems really spongy, even for peat moss. Another possibility is that it's soil liquefaction, where the ground sucks up water and assumes liquid-like properties. But again, it doesn't look exactly right. Or maybe this guy is bouncing on the roof of a troll's subterranean house — and he's flirting with disaster.

Any ideas, folks?