Waterboatmen ar insects in the Corixidae family. There are 115 to 120 species in the family. These insects commonly occur in freshwater ponds and may occasionally be found in streams and in brackish water pools.

Unlike many aquatic insects, the waterboatmen do not bite humans. Waterboatmen feed on algae, larvae and small aquatic animals. They use their paddle like arms to skim across the surface of calm water. Waterboatmen do not have gills. To breath under water, they grab air bubbles with their paddle-like arms and dive under water, breathing with the air contained in the bubble.

Waterboatmen generally are found in shallow water with aquatic plants to cling on. In shallow water, they don't need as long a trip to the surface to get an air bubble. It is not yet known what species of waterboatmen are found in the Hamakua Marsh, but is believed that the A'eo and the Moorhen will feed on them if they are available.