It must be very rewarding, I suppose long exposures are pretty much impossible with someone else in the picture, all the water movement and your partner moving.
Closest I got was leaning my camera just into the top of a flooded shaft on a tripod, the first pic worked quite well but then the waterproof case decided to not be waterproof and the camera died 😛
jeg elsker Norge, landets dialekter, folk, landskap og naturen!