The Energy Observer is a boat that makes its fuel out of seawater
 

Energy Observer is a vessel powered only by energy that it generates itself, be it the onboard solar panels, wind turbines or a hydrogen fuel cell. It's a floating laboratory, PR stunt and clean-energy evangelist all at once, showing how the future o...

https://www.engadget.com/2019/10/08/...en-power-boat/