Everyone remembers the classic Fred Flintstone car; a simple design made from rock, wood, and animal hide that is powered by the feet of those riding within it. Not only does the design solve the whole ‘internal combustion engines haven’t been invented yet’ thing, but it is also a completely sustainable design that provides quite a workout for the passengers.

Well, welcome to the 21st century version of the Flintstones car with the unveiling of a new design for a floating, mobile gym that is powered by, you guessed it, the people exercising within it.