Hi all. I was hiking at the Devil's Punchbowl in Hamilton yesterday, and on my way down to the level, I passed by a short but pretty looking drain (see photos; one from exterior, one from about half-way in).

I went in and noticed that around the time I got to the middle of the drain, the floor--which had looked like rough, unfinished or broken concrete--felt mushy. At first I thought I was imagining it or that my shoe was wet and squishy, but then it happened again with another step, so I decided to leave.

Just wondered if I was standing on top of some sort of major hazard that I wasn't aware of (i.e. I misunderstood what the drain floor is made of). Thanks!

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Mud, silt, sludge. Probably nothing toxic but that might depend on what is on the other side. Bring some rubber boots or waders as well as a good flashlight and you could probably get a good idea of what it is.

There'd be a concrete floor, right? So it would have to be mud/silt/sludge as Tomtortoise said, sitting on top of that. You could jam a stick down into it to confirm.

I've been there before. It's nothing dangerous, just make sure you have waterproof boots on ha. Having a partner always helps.

Thanks everyone. I immediately regretted not having a stick, in general, when I went down all the mud to get there.

If this were a mine, I’d be concerned about a possible false floor (shaft). Fortunately, the only infrastructure drains I’m aware of are made of concrete and typically don’t have vertical shafts for you to fall to your doom into because the hole was hidden by a thin layer of rotting wood.
Drains are built explicitly with moist conditions in mind in order to slow down the drain’s deterioration. I would assume you stepped on something in addition to the “floor,” that got stuck there or just some good old-fashioned toxic sludge.