The term ‘hot pool’ can vary in its interpretation of the word hot. I learnt this the hard way – by jumping naked into a lagoon in the middle of an Icelandic winter’s night. The water was invigorating to say the least. And yet, it was still warmer than the frosty surrounding air.

Iceland is a country built, quite literally, on hot water. A positive side effect of the tectonic faultline running diagonally across the country, which is responsible for its unique landscape of volcanoes and geysers, is the endless supply of hot water found in the geothermal springs below the surface. It comes in handy in a country sitting just below the Arctic Circle – you never have to worry about your shower turning cold. In fact, in the town of Hveragerdi, on the edge of a geothermal area in Iceland’s south-west, hot water is actually cheaper than cold.

We’d been in the country less than an hour before our first experience of Iceland’s love affair with hot water, at the iridescent Blue Lagoon. Having been greeted at the airport by the pitch black Icelandic night – at 4.30pm – it was even more surreal to find yourself floating in gloriously warm water as a frigid wind blew wisps of steam across the surface. The story of the Blue Lagoon’s rise to prominence – it’s actually the effluent of a power station, which became so popular as a local bathing spot that they spruced it up, turning it into the country’s No.1 tourist attraction – gives a fair indication of the Icelandic obsession for hot water.

Like the Swedes and their saunas, spas here aren’t just an occasional treat but a way of life. Despite a population of just 180,000, Reykjavik, the country’s capital, has multiple swimming pools, complete with adjoining hot tubs, and a dip is relatively cheap in what’s an expensive country. The pools, like the Blue Lagoon, have strict rituals associated with taking a dip, which can be confusing for first-timers. Having left your shoes outside the change rooms, and put your belongings in a locker, it’s compulsory to shower before taking a dip. This is done to kill germs, as Icelandic pools use little chlorine. You’re then free to flit between the indoor swimming pool and outdoor hot pools, of which there’s usually several at different temperatures. Suffice to say, resting your weary body in a 41°C hot tub in the pre-dawn light (at 9am), while the lightest of snow starts falling from the sky, is one hell of a hangover cure.

The geothermal springs are also put to more practical use. Iceland employs its hot water in a myriad of ingenious ways: to generate electricity, pumped beneath footpaths to prevent them freezing over, even to grow bananas in artificial greenhouses. Wherever you go, it’s impossible to escape water’s all encompassing presence: pipes beside the highway pump it back and forth, and Reykjavik’s standout landmark, six giant 4,000,000-litre hot water tanks, tower above the city, complete with revolving restaurant on top.

Water also provides many of the spectacular natural wonders that tourists flock here to see, whether it’s spouting from the Earth near Geysir, from which all the world’s geysers take their (misspelt) name, or thundering in the opposite direction at nearby waterfall Gullfoss. It’s also found in frozen form, in the country’s many spectacular glaciers, including Vatnajökull, the biggest in Europe.

It was after a day of glacier climbing that Karl, our guide, suggested a midnight swim. Having led us by torchlight kilometres into the wilderness, we soon discovered an abandoned 20m swimming pool that was being constantly topped up by a pipe running from inside the mountain. Goaded by Karl in the men’s changing hut into all swimming naked, it was a fast dash from hut to pool, made even more disappointing by the lukewarm water we jumped into. It was an indication of how far our expectations had come in just a few days: sitting in an unregulated pool in the subzero midnight air, complaining that the natural water temperature wasn’t quite warm enough. Talk about a wet blanket.