Surfing... the husband of our oldest studies bridge engineering. His master thesis is about surfing....
More and more young people attach bungee ropes to a bridge and surf. But there are risks: under water vortices or rocks, no rescue road along the river,.. So he works on designs how new bridges or bridges which have to be repaired can be made more safe for surfing, while still doesn't affect waterflow, bridge stability and nature too much.
Luckily our village bridge is a test object. Not too big, but very safe for kids learning surfing.