Sylvia Flat geothermal hot pool is next to the river in Lewis Pass.
Motoring the Mainland loop is a classic trip, finds Cameron Williamson.
Driving on to a big blue ship on an ink-black night in Wellington is a novel way to start a road trip.
At the oldest end of the city where barques once berthed, we park our car in the cavernous bowels of the Bluebridge Straitsman and check into our twin-berth cabin.
Friendly staff and shipshape accommodation - duvet-covered berths each side of a porthole; bathroom with shower and loo; emergency instructions in German and Danish - make this voyage something of an adventure. Old-world comfort spiced with Scandi chic.
We tuck up in one island port to wake up in another. The gentle ocean surge of Cook Strait in winter and the long run down Queen Charlotte Sound deliver a deep sleep and an early start on the road from Picton.
There's a full menu of tasty looking breakfasts on board, but I'm itching to get on the highway heading south, and the sun's not yet risen.
Darkness melts around Seddon and Jack Frost thaws by the Lake Grassmere salt works and we find the sea again south of Ward.
The Kaikoura coast at dawn must be one of the world's great drives: the road plaits with the railway down the rocky strip between sea and snowcapped mountain range and wetsuited seals line the road like hitchhikers. V formations of plump seabirds patrol the seafood-rich coast and crays-for-sale signs implore you to stop.
With easterly sun spotlighting the well-formed corners around Clarence and Ohau Point and light traffic, the couple of pre-breakfast hours of driving generate an appetite.
Nothing is open on the coast this early - even the superb homebaking of The Store at Kekerengu is shut. But in Kaikoura town's Beach House Cafe we find a crackling fire and a hot English breakfast.
Kaikoura is a cool place to meet coastal nature at its best: whales need watching, you can swim with seals and dolphins, and they are all here because paua and crayfish populate the rocky peninsula and anchor a veritable seafood platter for ocean dwellers.
Just south of town, we turn right into the mountains on Route 70. This curly sub-alpine scenic road twists and turns with river crossings, switchbacks and humps like the Whales Back Saddle. Bring your own gear changes and snow chains (just in case). Some of the few cars we see turn up the skifield road at Mt Lyford's log-built base lodge.
Waiau, on its braided river of the same name, delivers us into North Canterbury, and the long, loping straights across the plains are curtailed by a precipitous gorge crossing. We drive up an avenue of Californian redwoods into Hanmer Springs - historic resort, hot-pool heaven and home to of one of the country's quaintest resort hotels, the mission-style Heritage Hanmer.
The hotel has witnessed many shenanigans involving neighbours from the (sorely missed) alcoholics' haven Queen Mary Hospital, Christchurch power brokers and ghosts. Yes, there is a resident poltergeist in an upstairs suite.
There are two ways to enjoy this alpine arboretum: one is to get active with hired mountain bikes and pedal, climb, huck your way through the exotic forest's black pines, Norway spruce, larch, alder and oak (technicolour in autumn). Otherwise, take an all-areas pass to the springs and spa, relax with a manuka-infused massage, a mineral soak and some wild rides on the hydroslides.
Either way you'll leave with your musculature rearranged and renovated.
Back on the road, we turn right out of Hanmer on to Highway 7 and head for the hills. There are more rugged routes for four-wheel drivers - north through Molesworth Station or over the Rainbow (often closed in winter). But, for scenic tar-seal heaven, the beech forest blast through Lewis Pass is hard to beat.
We'd developed a taste for hot water after our Hanmer soak, and an hour up the road we stumble across the wild, build-your-own-boulder-pools upstream from the Sylvia Flats rest area. The natural springs bubble up in Lewis River's shallows and, with a bit of rearranging, we're soon submerged in 40C of fresh bliss. Only our heads are above the surface, which seems to be the signal for every sandfly east of the Alps to swarm and suck face.
We could have stopped at the country's most authentic onsen (Japanese-style scrub-n-soak hot baths) at Maruia Springs but we're excited to be over the Divide and heading for Murchison's famous merchandise.
The roll north up SH65 along the Maruia and Shenandoah Rivers is another distracting (for passengers) cruise - unpopulated, gloriously forested and remote enough to be restful. So hauling into the throbbing metropolis of Murchison - and more pertinently to one of the great second-hand emporia in the country - is like coming home from the hunt.
A couple of trophy purchases later (her mid-century turned-totara bowls; his quiver of old chisels) we're winding up the Buller on SH6 and lacing up for an afternoon walk at St Arnaud, HQ of Nelson Lakes National Park on the shores of Lake Rotoiti.
The beech forest circuit through habitat rescued from honeydew-plundering wasps is a piece of magical farawayland. It's also an environmental success story that is testament to hard graft by DoC and local volunteers.
The National Park HQ is worth a good long pause, but soon it's time to motor on up SH6 to Kohatu Junction, where a pub meal at one of the country's oldest staging posts makes a restorative break before a night in Nelson.
A couple of nights at Wakefield Quay B&B offers the alternatives of long, sunny, seafood lunches overlooking the Boulder Bank at the Boat Shed across the road, or motoring a circuit of Motueka, Upper Moutere and Mapua.
Nelson's and Tasman's inveterate producers of apples, hops and smoked seafood complement the vineyards that produce a dozen delicious wines, from gewurztraminer to pinot noir.
Our boot is well-stocked as we cross Pelorus Bridge over a blue-green river and wind through Havelock and Queen Charlotte Drive to Picton for our passage back to reality.
Motoring the Mainland loop in winter has inspired us to return in another season, and spring's not far away.
The trendy spot is just six minutes from the Waikiki beach.