What is NRBA riverboarding?????

Question

Tethered to shore,with extreme bungee systems,exceeding 30 mph up river....

Answer 1

River boarding is a body boarding sport in which the participant is tethered to the shore while the river flows underneath their board. It is physically analogous to water skiing but instead of being pulled through the water, the water flows past the river boarder. Elastic tethers allow for flexibility the location of the river boarder. Fast flowing currents are preferred.

Answer 2

NRBA stands for National RiverBoarding Association.  I've included some links with more info on the sport.

Matt