The couple were taken on a wild ride down the Otago river, soaring through spectacular canyons at speeds of up to 85kmh, in as little as 10cm of water.
Luckily, a glorious warm sun was beaming to counter the wind chill - the best weather of their New Zealand tour so far.
The duke and duchess were all smiles during their first 180 turn and the only screams to be heard were from the crowd of excited royal watchers. The boat then disappeared down the river toward the canyons before returning to the jetty for more spins.
The royal party burst into a round of applause after the ride, according to tweets from royal reporters.
There was no sign of wobbly legs as the royal couple stepped off the jet boat, both of them sporting broad smiles. William's All Blacks cap was still in place.
After thanking their hosts for the ride, the couple spent time chatting with a group of Arrowtown School pupils waiting on the river bank. Local girl Maggie Langford, 5, had earlier given the duchess a posy of flowers.
The boys looked particularly pleased to speak at length with the duchess. "Bye guys," William called as they slipped back into their car.
The couple headed off to Queenstown to spend the night in the luxurious Matakauri Lodge overlooking Lake Wakatipu.
The steering wheel on the royal jet boat ride was entrusted to one of the operator's most experienced jet boat drivers.
Wayne Paton has more than 5000 hours of jet boat driving, Ngai Tahu Tourism southern general manager David Kennedy said.
The duke and duchess were seated in the second row of the 15-seater jet boat, flanked by young Ngai Tahu representatives, whom they greeted on the bank and posed with for a photo.
Tribe elders and youth, Kaumatua Sir Tipene O'Regan, chairman Sir Mark Soloman, Kensington Palace representatives and, of course, the couple's security, also had seats in the two-boat river convoy.
A TASTE OF CENTRAL
Thrilled crowds glimpsed a waving Kate and William earlier as they drove into Amisfield winery. Over 1000 people crowded the road and waved flags as the motorcade arrived.
The couple were there for a tour of the vineyard and a talk about Central Otago wine, before a short but exciting ride on the Shotover Jet.
They were greeted by co-owner John Darby and Central Otago Wine Growers' president James Dicey.
Gibbston wine region founder Alan Brady gave William and Kate a brief overview of the area's wine history inside Amisfield, where more than 20 local winemakers were waiting to serve samples of the best local drops.
William and Kate landed in an Air Force plane at Queenstown airport at 2.15pm.
They were greeted by Queenstown Lakes District Council Mayor Vanessa van Uden before being whisked into a 12-vehicle motorcade to Amisfield.
The duchess left the plane in her third outfit for the day - skinny jeans, a checked shirt, wedges and a navy Zara blazer.
A small crowd gathered at the edge of the airfield to wave at the motorcade.
WILLS EVENS THE SCORES
Earlier, William bounced back from his 2-0 sailing defeat at the hands of his wife Catherine on Auckland's harbour last week with a victory on the rugby field.
During a ripper Rugby showdown in Dunedin, the duke's team Clutha bet Pirates 30-20, with Clutha seven-year-old Chase Te Moananui-Currie stealing the show with three tries, a this afternoon.
The rugby field at the Forsyth Barr stadium seemed to be more his natural environment as he shared tips with All Black Richie McCaw on the sidelines during the game.
It was another peek into the royal couple's relationship and their competitive streaks. The Southern audience seemed to be just as excited about the close rugby match as they were about catching a glimpse of the royal pair.
But at half time the royal couple huddled with their teams, made up of seven and eight-year-olds, and shared slices of oranges, a change from their normal gourmet menu.
The future All Blacks did not seem starstruck by their high powered coaches, more focused on winning the trophy than rubbing shoulders with their royal counterparts.
Kate looked elegant as always, stepping out on to the field in a Jonathan Saunders jumper.
A MOMENT OF WORSHIP
This morning a crowd of thousands gathered outside St Paul's Cathedral in Dunedin waiting to see the pair.
Running late for the Cathedral's Sunday service, the royals did not stop to chat to a 4000 strong crowd on their arrival in the Octagon.
Their Air Force plane touched down in the southern city about 9.30am.
Kate was wearing an aquamarine dress by New Zealand's Emilia Wickstead, the first time she has worn a Kiwi designer. The outfit was topped off with a Jane Taylor hat and a fern brooch.
The city prepared a royal welcome for the couple, including a civic powhiri led by Dunedin mayor Dave Cull and Otago runanga chairman Edward Ellison at the Dunedin International Airport.
After that they headed to a palm Sunday service at Anglican Cathedral St Paul's in the Octagon.
Prince William and his wife Catherine wanted to participate in Sunday worship while in the city, as they would at home or wherever in the world they were, Anglican Church communications advisor Reverend Jayson Rhodes said.
Reporting by Joelle Dally, Debbie Jamieson, John Edens, Louise Berwick, Kevin Norquay and Wilma McCorkindale