Also see https://www.youtube.com/watch?v=K_nnUbX7uuQ&t=6s I went to Widemouth Bay and checked out a few interesting manhole covers myself. It was pretty awesome. When I told my family they thought I was joking, but I'm guessing some of you people might understand.

I like this one, too: https://www.theverge.com/c/24070570/internet-cables-undersea...

You beat me to it!