Thermonectus marmoratus is a relatively colorful North American species of diving beetle known by the common names sunburst diving beetle and yellow-spotted diving beetle. The behavior of this diving beetle has been compared to a scuba diver, since it carries with it a bubble of air as it dives down into the water. Its aquatic larval stage was the first ever recorded use of bifocals in the animal world. The beetle uses in its principal eyes two retinas and two distinct focal planes that are substantially separated, in the manner of bifocals to switch their vision from up-close to distance, for easy and efficient capture of their prey.

Because of their bright aposematic colors, they are often displayed in zoos, sometimes together with Abedus herberti (also found together in the wild) and other aquatic beetles.

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