It looks like the red balls keep it afloat. The paddles on the outside of the red balls, paddle. I assume the inside cage remains upright and the two outside circles of balls and paddles rotate as the person runs. What's unknown is:
- can he steer,
- can he only rotate one wheel at a time?
- Can he take a break?
- Restroom facilities?
- Can it withstand a shark attack?
- Is there sunshade?
- Compass?
- Communications?
- Does a large wave reverse the paddle direction and rotate him?