https://www.youtube.com/watch?v=Gfn4taDi0EA
https://www.youtube.com/watch?v=jirDGL6vL1A
Behold: the deeply satisfying, slightly alarming ’sport’ of tethered hydroplane racing where motorised hydroplanes are tethered to a central point in ponds then released, whipping round at speeds up to 217km/h (135mph).