When soaking in a magma-fuelled hot spring within a volcanic caldera* I decide it's best to adopt a philosophical air.

Really, if the volcanic basin that is spread out before me in the form of a lake suddenly erupted, there would be nothing I could do. So I might as well sit back, relax, and let the deep molten magma below the Earth continue to heat the pool in which I'm immersed.

Over the years, Rotorua's therapeutic waters have soothed much, much more than just my volcanophobic mind. In fact, it was the region's thermal water - and its therapeutic properties - that brought tourists from across the world 200 years ago.

In the early 1800s, visitors flocked from as far away as Europe to bathe at the Pink and White Terraces. Considered New Zealand's first tourist attraction, the terraces offered visitors not only a spectacularly obscure display of white and pink silica rock formations, but also therapeutic bathing in the natural hot springs created by the volcanic forces at work below the ground.

Unfortunately those same volcanic forces were what brought the terraces (and 150 people) to their demise, when Mt Tarawera erupted in 1886.

Also around this time, an Irish Catholic priest who suffered debilitating arthritis heard about the town's therapeutic waters. Trekking 80km to Rotorua from his home in Tauranga, Father Mahoney dug himself a pool, set up camp beside it and began to bathe frequently in the thermal waters. A few months later, Father Mahoney's arthritis was cured and word began to spread...

Today, the same spring in which Father Mahoney bathed is known as the Radium hot spring, and feeds the fittingly named 'Priest Spa' at Rotorua's internationally acclaimed Polynesian Spa complex. The three Priest Spa pools range in temperature from 39C to 42C and their acidic water is still touted as a therapy for tired muscles, arthritis and rheumatism.

The rest of Polynesian Spa's 26 thermal pools are filled with alkaline water. Sourced, near-boiling, from the nearby Whangapipiro spring, the water is cooled to between 36C and 39C with water from the town supply.

Sliding into the 36C pool is heavenly on a grey June afternoon. Returning to it after a soak in the 38C, 39C and 42C pools, however, renders it tepid at best!

Pool-hopping at Polynesian Spa is the norm. The short dash across the beautifully landscaped setting is restricted only by your will power to extricate yourself from one pool to scurry to the next. From the relaxing comfort of each pool you can look out, past the decorative trees and rocks, to the splendid Lake Rotorua: that volcanic caldera that has me feeling so philosophical.

Mt Tarawera's eruption in 1886 was the most recent volcanic activity in the area, but here in Rotorua there are still rumblings of fury from beneath the Earth. It's evident in the steam that swirls from cracks in the pavement; in the strange, frosted rock formations that skirt the city; and in the sulphuric scented water that bubbles up from below and soothes me, volcanophobic mind and all.

*A caldera is a volcanic basin formed when the Earth slumps following the emptying of a magma chamber during volcanic activity. These depressions are then usually filled with water, creating deep lakes.

Amelia visited Rotorua courtesy of the Tourism Industry Association of New Zealand and www.fourcorners.co.nz. She was a guest of Polynesian Spa.