Whitewater sledging, or hydrospeed, involves riding a custom-designed river sledge through rapids. Hydrospeed puts you in control, as opposed to rafting where the guide does the steering.
Sledging is a more extreme activity compared with whitewater rafting, which means that sledgers need to be strong swimmers.
Kaitiaki Adventures and Raftabout run whitewater sledging (hydrospeed) trips on the Kaituna River. A 3½ hour trip on the Kaituna River costs $120–129.