Fathom Fan is one of the unreleased toys from the second year of the Centurions toy line. It was featured in later episodes of the TV series. In universe, Fathom Fan is an Assault Weapon System for Max Ray. It's a airboat-like vehicle that skims along the surface of the water, powered by a large propeller backpack. Its weaponry includes chest-mounted lasers and two sea-skimming missiles that launch from the pontoons.
Information on Fathom Fan is scarce. While it was used in the TV series, Kenner never included it in their dealer catalogs, and no artwork of the system (outside of its TV appearances) has ever surfaced. If a complete Fathom Fan prototype ever existed, to date it has never been seen in public; however, some individual parts and molds are known to be in the possession of private collectors.