I used to teach canoeing lessons to Boy Scout troops at a local neighborhood lake. Super small lake that’s not very deep but the bottom was hella thick with vegetation. The water was “dark” so you couldn’t see your hands in front of you for more than like 5 inches under the surface. There was a small clubhouse, an open pavillion, and a playground all on the property.
When doing lifeguard work in the water during a swim test, my sunglasses fell off my head. I dove down to find them and s@#t you not – I found a sunken, entangled hospital gurney at the bottom of the lake. It took a few people to untangle it but how the eff it got there was beyond me. Clearly it had been under the water for years…