Volcanic activity created all nine major islands of Portugal's Azores archipelago, forcing them up from the seabed until they towered above the Atlantic. The Lake of Fire is so named because in 1563 one of Azores' many volcanoes exploded, creating a massive caldera of super-heated lava.

Below the Lake of Fire (on the northern side of this banana-shaped island known for growing ''the sweetest pineapples on the planet'') is one of Europe's largest geothermal plants, providing Sao Miguel with a third of its electricity.

And in between?

There's the Caldeira Velha, known for its walking trails, its waterfall - and its volcanically heated hot springs.

Striding to the top of the 200-metre trail, I pass hissing steam from bubbling streams on my way to the top waterfall.

I spot a grandfather taking an open-air shower under the waterfall while his wife at the pool edge videos him on her phone. ''He's doing it for our grandkids,'' she explains.

It's only after I join him in the waterfall I realise how stoic he is.

This waterfall may not be freezing (it's April) but it's definitely chilly.

I head a few metres down the hill to join those basking in the real hot pools. They're the ones who have been in the steaming water so long they look vaguely poached.

Sao Miguel is the largest island in the Azores (a two-hour flight from Lisbon) and Ponta Delgada is the archipelago's main entry point, by air or cruise ship.

Tiny shops in tiny streets - designed for donkeys not cars - sell wheels of local unpasteurised cheeses, doughnut-like pastries, hand-embroidered cloths or Catholic statues.

If you have an four hours to spare, join a 4WD tour exploring the even less crowded and unhurried lanes of Sao Miguel's magnificent mountainous interior.

That's how I found myself at Caldeira Velha's hot springs and the Lake of Fire.

The island is blessed with three massive calderas, all now filled with lakes constantly replenished by rainwater. At the western end is the most famous, the Lagoa das Sete Cidades. At the eastern end is Lagoa das Furnas, near the village of Furnas, known for its hot springs and hiking.

But the Lake of Fire is the highest and the only one supplying drinking water to the islanders.

I know this only because of our Canadian-accented driver and guide, Elvis.

Honestly, you couldn't make this up.

His parents' first date was spent watching Elvis Presley in Viva Las Vegas and they pledged to name their first son after ''the King''. This Elvis was conceived in Sao Miguel but born in Ontario after his heavily pregnant mother took her first flight from Sao Miguel to join his father. The 1950s and '60s were times of mass migration from the Azores to the Americas.

But this adult Elvis not only left the building, he returned to Sao Miguel.

During our back-lane journey we see goat herds; face off tractors whose drivers are racing to do the afternoon milking; and witness a steep, sweeping landscape blessed with so many wild flowers it is beloved by botanists.

''Sao Miguel is known as the 'the green island','' Elvis says. ''Think of it as the love child of Hawaii and Ireland.''