I’m siding with @fuzzyfungus here 
My parents have a small pond and there typically were a few of these in it. I loved watching them. I haven’t seen them for the last few years, but there’s some other smaller species of diving beetle there now.
We also have other large and amazing looking beetles, possibly great capricorn beetles, but the color is a bit different , I posted photo here:
Post your Pet or animal Pics (Part 1) - #2212 by 74hc595
