The royal couple, who are taking their son, Prince George, with them on their three-week trip, will go head-to-head in a sailing contest on Auckland harbor on April 11.
In the same way that they competed against each other in a dragon boat race during their 2011 visit to Canada, the pair will be taking to the water in New Zealand aboard dueling America's Cup yachts.
"They are a little competitive and we expect this to be very enjoyable," William's private secretary, Miguel Head, said during a press briefing.
William won the dragon boat race last time, so perhaps this time Kate will even the score.
The adrenaline rush will continue two days later when they take a 50-m.p.h. white-water ride across the Shotover River in a jet boat. "It's a spectacular experience," Head says.
Another of their New Zealand stops will include coaching teams in a game of Rippa rugby (a non-contact version of the football game) alongside some of the country's famous All Blacks rugby players. Expect "competitive outbursts," Head says.
Humanitarian Stops in AustraliaIn Australia, William and Kate will travel to the Blue Mountains on the outskirts of Sydney to meet local residents who were affected by recent bush fires.
Kate, who is the patron of a children's hospice in the U.K., will also be visiting facilities in both countries that offer palliative care to sick kids.
And on April 22, the couple will head to the Outback to visit Uluru, a large sandstone formation in the middle of Australia that is sacred to the local Aboriginal people.
Kate is traveling Down Under for the first time and "it's something she's always wanted to do," Head says. "She's very excited."
He continues, "The breadth of, and variety of, things they're going to be seeing and the people they're going to be meeting makes her very enthusiastic about the visit. Both of them are very outdoorsy, sporty people." And because both countries are known for their love of sport, "having a chance to be a part of that is very exciting."
The couple's whirlwind tour will take in the New Zealand cities of Wellington, Blenheim, Auckland, Hamilton, Dunedin, Queenstown and Christchurch, and in Australia they will visit Sydney, Brisbane, the Adelaide area, Uluru and Canberra.
"There's no hiding the enthusiasm for this visit by both the Duke and the Duchess," Head says. "The Duke, because he has been before, and the Duchess because she has never been to either country but has wanted to do so for as long as she can remember."