One of the big draws for Iceland is of course the geothermal effect on its waters. People flock to resorts like the Blue Lagoon to sit in warm water and cold air. To sip drinks, make Instagram worthy poses and relax in the luxurious surroundings. I didn’t really fancy it; too busy, too posy and needed to be booked well in advance. So we made a couple of other plans.

First up, the secret lagoon. Shhhhhhh! Don’t tell anyone. On the outskirts of Fludir, it was the oldest swimming pool in Iceland and although had at one point fallen into disrepair it is now reopened. There is a cafe and showers and changing rooms, but it’s not too boutique. There was quite a bit of posing going on though… We laughed at the lifeguard protected from the cold air and wind in a glass box, dressed in several layers and still looking chilly.

There are two areas where the water enters, a mini geyser throwing up spouts of warm water and plumes of steam. These are fenced off but you feel the change in temperature as the warmer waters drifts across. 38-40C is the estimate. Almost too warm for me. We were both reminded of the Christopher Brookmyre titular tale… Only 1m deep in places and with a couple of dozen people, it wasn’t really all that suited for swimming. But I managed a few strokes here and there as we both chilled out in the soothing waters. JT had a lesson in ice cream headache from cold air. Neither of us felt the urge to walk the perimeter boardwalk to cool down before a second dip.

And then the main event. We checked it out one night, but the long hike earlier meant we were flirting with dusk. We didn’t quite get to the pool, but met a local who confirmed where it was. He was showing it to a friend who hadn’t been before. His verdict? “I fucking love it”. So back on the day we left the hotel Umi.

Seljavallalaug. Definitely nothing boutique here. Built in 1923 it is in the valley below the Eyjafjallajökull volcano. You drive off the ring road then 2km or so along a gravel path to the parking area before walking 15 minutes into the valley. And we had it to ourselves early morning. JT didn’t venture in. Warm but not boiling, the pool is covered in algae as not treated and the changing rooms are a little, eh, basic. But it was absolutely wonderful. In the amphitheatre of the valley, the pool has been fashioned at the edge of the mountain. The water flows into the deep end furthest from the hut. You enter near the hut into the warm water and it gets hotter as you get towards the car park end. And once you turn, what had felt warm now feels cool.

As I swam a few flakes of snow started falling and the wind whipped the water up until it felt like hailstones on my face each time I turned to breathe. Invigorating, life enriching, I laughed to myself as I swam on (trying not to swallow anything, just in case). JT patrolled, taking photos, admiring the startling blue in the river, warning me of others approaching. So much for the skinny dip. Knowing we had a long drive ahead and not knowing how cold I’d be on the walk back out, I only swam maybe 400-500m. Definitely one for a return visit. Swimming heaven especially when you are on your own. As the man said, I fucking love it.