In Shadow Generations, Doom Surf is one of the Doom Powers that Shadow the Hedgehog can utilize to his advantage. When Shadow touches water, he automatically summons a black manta ray-like construct with red eyes and patterns. In gameplay, Shadow can freely surf and jump across the surface of any body of water. He can jump off of ramps and move through Dash Rings. The Quick Step becomes the "Surf Spin", a type of Spin Attack, which can be used to ram into objects to launch them or destroy them.[1]
Sonic Speed Simulator
In Sonic Speed Simulator, the Doom Surf appears as part of Doom Shadow's moveset to promote the release of Sonic X Shadow Generations. Whenever Doom Shadow goes into any large area of water, such as No Place, the Doom Surf will activate automatically and serve as a "Mount". Attempting to unmount from Doom Surf will only make it activate again. If the player utilizes an Extreme Gear, however, Doom Surf will not appear until they unmount the hoverboard itself. Additionally, Doom Surf is the only one of the three Doom Powers used by Doom Shadow that can be used even without activating the Doom Wing.
Shadow launching projectiles at Metal Overlord using the Surf Spin.
Terios using the Doom Surf.
Terios using the Doom Surf.
References
↑Sonic Team (22 October 2024). Sonic X Shadow Generations (in English). Nintendo Switch. Sega. Area/level: Q&A - Doom Surf. "Move quickly on water. Press or to perform a Spin Attack. Press when starting to Doom Surf to quickly accelerate."
or 
to perform a Spin Attack. Press 
when starting to Doom Surf to quickly accelerate."