The first thing everyone wants to know when they see the sQuba is: Why the heck would you make an underwater car a convertible? It does seem to be a significant drawback. Ideally, underwater day-trippers would prefer to stay warm and dry while they glide past shipwrecks and anemones. There are several good reasons for designing the car without a roof, however.
To clear one thing up, the sQuba isn't a convertible in the conventional sense. It's an open-top car, designed not to have a roof at all. The first reason for the open design is safety. When an enclosed car falls into the water, the pressure of the water pressing against the doors and windows makes them difficult, if not impossible, to open until water fills the car and equalizes the pressure. In an emergency, sQuba occupants could be trapped in their underwater car if it was enclosed.
The other reason has to do with buoyancy. An enclosed car would have to be airtight. The result would be a large bubble of air in the middle of the car, increasing the buoyancy (the tendency to float) of the car. To counteract this buoyancy and allow the sQuba to stay below water, Rinspeed would have needed to add about two tons to the car's weight, and even then, it wouldn't go very deep. It would also accelerate and handle like a large brick on land.
The driver had better keep a change of clothes (or some towels) in a waterproof bag, but the car's interior has nothing to worry about. The seats were designed by Strähle + Hess and feature a fabric insert that uses capillary action to draw moisture out of the seats when the car is on land. The fabric also resists weight gain when underwater. VDO Automotive designed the instrument panel, a single aluminum housing that protects the electronics within from water up to a depth of 10 meters. The control buttons are covered by a plastic layer that offers similar protection, yet allows driver manipulation even while wearing diving gloves. All surfaces and items are impervious to salt water, so sQuba drivers can dive into ocean water as well as freshwater lakes and rivers.
In the next section, we'll learn how environmentally friendly the sQuba is.