New Zealand has 9,400 miles of coastline plus hundreds of freshwater lakes and more than 125 whitewater rivers. Sailors blow around Auckland. Surfers kick back in funky Raglan. Whitewater paddlers gather on the South Island's west coast, where milky Class V (and lesser) rivers rush to the Tasman Sea. Sea kayakers cruise all over. Which is to say, there are options.
An aggressive way to start: crewing a three-hour head-to-head sailing race on the retired 80-foot America's Cup yacht NZL 41 in Auckland's Waitemata Harbor ($150; explorenz.co.nz). For longer cruising adventures, the Bay of Islands, the archipelago off the northeast coast of the North Island, has summer temps in the high sixties and seventies, steady breezes, and some 150 islands with safe harbors. Great Escape Yacht Charters rents Davidson 20's ($90 per day) or Noelex 25's ($120 per day; greatescape.co.nz).
Surfing in New Zealand means packing a 5/3 wetsuit and, if you're after serious swell, coming in the winter (April to June). Bring your shortboard and drop in on Raglan (on the west coast of the North Island), home to "the longest left in the world," which is actually a series of three left-hand point breaks that jut from the foot of a dormant volcano. Crash at Solscape (close to hot spots Manu Bay and Ngarunui Beach), a beach house made completely from recycled timbers and native bricks (studios from $105; solscape.co.nz).
Starting a rafting trip in a helicopter generally leads to good things. Hidden Valleys offers two-day trips on the Class V Perth and Class III–IV Whataroa rivers. You'll fly to a gentle stretch of the snow-fed Perth, then drop steep gorges through temperate rainforest before flying to the put-in of the Whataroa, which offers Southern Alps views on the descent to the west coast ($670 per person; hiddenvalleys.co.nz).
Sea-kayaking Milford Sound is a classic Kiwi adventure, but nearby Doubtful Sound, in Fiordland National Park, is more than twice as long and much less visited, because getting there requires a 19-mile ferry ride across Lake Manapouri, followed by a 14-mile bus ride. Adventure Kayak & Cruise leads day trips and overnight outings past 722-foot Helena Falls and Commander Peak, which stands almost 4,000 feet over the water (from $182; www.fiordlandadventure.co.nz).