Water beetles
Water beetles aren't a monophyletic group and can be found throughout the Order Coleoptera. So displaying or searching for water beetles requires a bit more effort. Here are links to most aquatic and semi-aquatic beetles found in the U.S. So if you find something that you know or think is a water beetle, scroll through this collection of species to help narrow down your identification.
Water beetles of the U.S. (change location to whatever you wish).
This link includes the following groups: Hydrophilidae, Dytiscoidea, Haliplidae, Gyrinidae, Scirtidae, Noteridae, Amphizoidae, Hydroscaphidae, Lutrochidae, Dryopidae, Elmidae, Heteroceridae, Limnichidae, Psephenidae, Sphaeriusidae.
