Sunburst Diving beetles live in freshwater rivers, streams, lakes, pools, and even hot springs of the northern regions. Unlike other water beetles, which swim by moving legs alternatly, the sunburst diving beetle flexes it's hind legs together simultaneously. Sunburst diving beetles can remain underwater for a long time, by breathing air trapped under the elytra. Their strong sickle shaped jaws can attack prey larger than themselves.

Source: www.enature.com