The Underwater Exo-Suit (also called the Aqua Scooter) is a turbo-vortex propulsion device. Stored in the undercarriage of Thunderbird 4, this exo-suit is used in underwater rescues where Thunderbird 4's plasma cutter or mechanical grabs isn't a viable option. The suit was first seen in Under Pressure and has also made an appearance in City Under the Sea, both situations requiring Gordon Tracy to go E.V.A to preform precision cutting with the suit's duel plasma cutters.
The Underwater Exo-Suit is stored in the undercarriage of Thunderbird 4. To equip it, Gordon swims into the suit and holds onto the grips located at the end of the arms where the plasma cutter and underwater operations are controlled.
This suit has a slight variation in the plasma cutter arms, in Under Pressure the arms of the suit are black while in City Under the Sea the arms have a proper yellow colouration on them.