Animals that are surprisingly rare

I can get a pictures of (invasive) European carp in a local man-made lake in a nearby park. Prolly, lost goldfish, or descendants of such.

https://www.inaturalist.org/observations?place_id=97394&subview=grid&taxon_id=53911&user_id=teellbee

But, I recall my former boss made a simple underwater viewer. It was a wide tube, maybe 6-8” in diameter into which he glued a plastic lens at one end and handles at the other. When you lowered it into the lake, it gave a small, but fairly clear viewing area (depending on water clarity).