https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/4022854
The Shotover Jet.
A jetboat is a boat propelled by a jet of water ejected from the back of the craft
. Unlike a powerboat or motorboat that uses a propeller in the water below or behind the boat, a jetboat draws the water from under the boat into a pump inside the boat, then expels it through a nozzle at the stern.
Jetboats were originally designed by Sir William Hamilton (who developed a waterjet in 1954) for operation in the fast-flowing and shallow rivers of New Zealand, specifically to overcome the problem of propellers striking rocks in such waters. Original public domain image from Flickr
Public DomainFree CC0 image for Personal and Business use