The shallow, braided rivers of the high Canterbury sheep country posed access difficulties for run-owner Bill Hamilton, who got around the problem by inventing the Hamilton Jetboat . His inspired invention could plane in as little as 100mm of water, reach prodigious speeds (up to 80km per hour) and negotiate rapids while maintaining astonishing turn-on-a-sixpence manoeuvrability.

The jetboat carried its first fare-paying passengers on a deep and glassy section of the Shotover River, which is still used by the pioneering Shotover Jet. Over half a dozen companies now run similar deep-water trips around Queenstown, while at nearby Glenorchy there's a wonderful wilderness trip along the shallow and twisting Dart River. Other key sites include the Wilkin River at Makarora and the Waikato River immediately below Taupo's Huka Falls.

Thrills-and-spills rides ($60-70) tend to last for around thirty eye-streaming minutes, time enough for as many 360-degree spins as anyone really needs. Wilderness trips ($50-100) can last two hours or longer, pacing their antics.