Every couple of days I find one or a few of these in my pool and the other day a big one so time to Google and find out what they are. My neighbors think all unfamiliar bugs are or could be dangerous and I've always scooped them out before they get here. Turns out they are all over the US, Canada and Mexico plus the rest of the world. I assume they live in all these rain water ponds around here and are attracted by my security lights near the pool.
Habitat and conservation: These beetles prefer quiet water at the edges of ponds and streams, floating gently among weeds. Before diving, they trap air between their wings and body, prolonging their time under water. Because predaceous diving beetles are strong fliers, they can fly away to new water if the pond they are in dries up, or if electric lights lure them away from “home.” This is why water beetles are sometimes found in birdbaths and swimming pools.
There are many, many different species of beetles, including hundreds of different predaceous diving beetles. If you are having trouble identifying them, congratulate yourself if you can say for certain that it's "some kind of a beetle"!
The movie shows three mating attempts including the two species Acilius sulcatus and Acilius canaliculatus, where the first two attempts are followed by matings, while in the third the female escapes.