We lay back, steam rising all around us, gazing at the upturned salt shaker of stars above Lake Tekapo's hot springs. The 39-degree waters penetrate our muscles, seeming to almost dissolve them.

This is what my husband and I have needed – a nature-fuelled break from reality, where we can simply sit and look at each other's faces for more than three seconds. Crazy as it sounds, it's taken us travelling all the way to New Zealand's South Island to do this.

The following morning we rise early to wander the shores of milky turquoise Lake Tekapo, which we drove three hours to yesterday from Christchurch. Hands entwined we stroll by the water, fantasising about staying a while to spend our days fishing, kayaking, hiking and horse riding through the surrounding Southern Alps.

Alas, a poke around the 1935 stone Church of the Good Shepherd is all we have time for before it's time to hit the road again.

Not that that's anything to complain about. The one-hour drive to Aoraki Mount Cook is nothing short of a tonic for the soul. We hug electric blue Lake Pukaki as we head up the Tasman Valley, passing undulating brown pillows of land smattered with green tussocks, then arriving at flat yellow plains with towering snow-capped mountains closing in around us.

Driving into Mount Cook Village, huddled into the base of New Zealand's highest mountain (3764 metres), we giggle like kids at the fairytale beauty of this place.

Our smiles, however, are wiped away two hours later as we start our Glacier Explorers "expedition" to see the 500-year-old Tasman Glacier. Strapped into life vests we head out in small yellow boats onto the terminal lake, passing icebergs as we go. Soon we reach the glacier itself, looking like a giant turquoise agate crystal popping out of the water and extending back into the mountains.

"This glacier is melting unbelievably quickly," says our guide. "If you were to come back in a year, about 150 metres in length will have melted away." The reason for this, he says, is the lake itself. The warming water is melting the glacier's underside so pieces are constantly breaking off and shortening it. It's a heartbreaking reminder of the effects of global warming, and the fragility of our planet.

Our sombre mood doesn't hang around for long, though. Not with all that delicious New Zealand pinot awaiting us back at The Hermitage hotel in the village. And not with the Hooker Valley Track drawing us back out into the wilds the following morning. The four-hour hike sees us weaving past majestic mountains as avalanches crash around us, picnicking at glacial Hooker Lake and crossing narrow bridges over the Hooker River, suspended over the opaque blue waters.

Suspension is the word du jour again the next day when, after another stunning three-hour drive to Lake Wanaka, I find myself hanging off the side of a cliff. I've signed up for something called Wildwire, where you climb 300 metres up the rock face alongside Twin Falls waterfall.

I'm wearing a harness and am securely clipped into the strong rungs we're climbing up, but none of that stops my legs from turning to jelly, my heart from racing or, mortifyingly, my tears from flowing.

Thank goodness for Mark, the ex-mountaineer owner and creator of Wildwire, who pep talks me out of my panic and up the sheer cliffs to the top of the climb.

The view, across vivid green fields to craggy mountain peaks with the waterfall rushing behind us, and the sense of self-empowerment I'm left with, makes it all worth it. I feel like I'm floating above the world.

As dusk gradually blots the light from the sky, we gobble a celebratory feast involving loads of pinot noir and a delicious sunflower seed risotto at The Landing restaurant.

Afterwards, we end our South Island adventure just as we started it – submerged in warm water, steam rising all around us under a smattering of stars. This time we're in twin claw-foot bathtubs outside our room at our B&B Tin Tub, clinking glasses to this natural paradise that has reconnected us not only to each other, but also to ourselves and to our planet.

TRIP NOTES

MORE INFORMATION

See www.newzealand.com

GETTING THERE

Air New Zealand operates multiple daily flights between Sydney, Melbourne, Brisbane and Christchurch; see airnewzealand.com.au

STAYING THERE

Tin Tub is a family-run hideaway five minutes from Wanaka town, with views over the lake, and a tennis court and pool. Choose between the lodge (sleeps four) and three luxury villas. From $280 a night; see tintubwanaka.co.nz

Nina Karnikowski travelled to  New Zealand with the assistance of Air New Zealand and Tourism NZ.

FIVE OTHER THINGS TO DO ON YOUR SOUTH ISLAND ROAD TRIP

1. TEKAPO STARGAZING

Tekapo is part of an International Dark Sky Reserve, making it one of the world's best stargazing sites. See constellations and shooting stars with Earth & Sky's tour of Mount John Observatory. $140; earthandskynz.com

2. AIR SAFARI

See New Zealand's peaks and glaciers from above with an Air Safari scenic flight from Lake Tekapo. From $350; airsafaris.co.nz

3. GUIDED KAYAK TRIP

Explore Lake Wanaka's coastline on waters so still they mirror the mountains. Half-day tours $90; wanakakayaks.co.nz

4. ECO ADVENTURE

Take a boat to Lake Wanaka's pristine Mou Waho, where you'll picnic with NZ's iconic weka birds, plant a native tree, and swim in the island's lake. $210; ecowanaka.co.nz

5. CARDRONA DISTILLERY

Tour and taste artisan spirits at this new family-owned distillery, set in a beautiful schist rock building between Wanaka and Queenstown. cardronadistillery.com