Hydro Thunder is a Motorboat racing sub-series game, originally an arcade game and later released for the Sega Dreamcast as a launch title in 1999.

The gameplay of Hydro Thunder consists of racing high-tech speedboats through treacherous environments, from the cold seas of the Arctic Circle, to a post-apocalyptic, flooded version of New York City.

Scattered across the tracks are blue and red boost icons. When touched these icons allow the player who touched them to boost. Red boost icons are more scarce than blue boost icons due to the fact red boost icons give more boost fuel. When a player has boost fuel they may use the boost button to boost, which allows a player's boat to reach speeds much higher than what would normally be possible. Also by boosting a player can knock other boats into the air, a feature described by the game as the Mighty Hull. Another aspect of boosting is the Hydro Jump which is performed by braking and using the boost button. When combined with the many ramps on the tracks, players can reach short cuts and boost icons that would normally not be accessible otherwise.