It seems clear that our ability to more efficiently harness forms of renewable energy is vital to the future of our planet, but aside from the archetypal 'hamster in a wheel', few models have effectively relied on energy generated from living creatures. The River Gym is one of the more innovative concepts to break water in recent times and looks to cash in on our desire to exercise to stay fit and healthy by capturing the energy we expend when burning calories.

This inspired design is the brainchild of architect and eco-designer Mitchell Joachim, who holds a PhD from the Massachusetts Institute of Technology. Intended to travel in a 15-minute circuit around the Hudson and East Rivers in New York, the River Gym 'pods' would offer a range of exercise equipment capable of converting energy derived from human motion into usable electric energy stored in on-board batteries.

The vessels would be fitted with water purification devices to combat pollution and would also be capable of carrying additional passengers and commuters, thereby easing the burden of ferry lines as well as varying the intensity of the exercise.

Multiple vessels would vary in size during peak and off-peak hours, depending on the volume of passengers,

As well as the obvious benefits of exercise and eco-credentials, spectacular panoramic views offer unique variety for passengers that far surpasses the bland tedium of a conventional gymnasium, and modest docking facilities would include lockers, a reception desk, health food kiosks and more.