I've always loved open-water swimming, from the adrenalin-infused January cold of Loch Eil – where the British commandoes trained – to snorkelling off coral reefs in Belize. So, in a pub on a Friday night in Glasgow, when I got chatting with a modern-day Viking, he piqued my interest as he declared "Swimming is Iceland's national pastime" and my mind was transported to a frozen land of majestic mountains and crystal-clear lakes. Two months later, I was in a suburb of Reykjavik, ready to plunge into the ice-cold sea. Iceland conjures up images of epic Tolkienesque scenery. So, I was slightly confused when I turned up at Nauthólsvík Geothermal Beach, sandwiched between an airport and a random collection of buildings. At first, I thought I was in the wrong place. However, I followed the steam to find a brutalist concrete structure with hot spring baths behind the beach, looking out to sea. I'm a traditionalist – I want snow and cold – none of this winter