While in the Reykholt area, it’s well worth checking out the biggest hot spring in Europe, Deildartunguhver, which lies near the hamlet of Kleppjárnsreykir, 5km west of Reykholt on the side of Route 50. Drawing on the geothermal reserves that lie all around Reykholtsdalur valley, and pumping out a staggering 180 litres of 97°C water a second, the billowing clouds of steam created by this mighty fissure are truly impressive, reaching up high into the cool air – in fact it’s water from here that runs via two specially constructed pipelines to heat Borgarnes and Akranes, 34km and 64km away, respectively. As in so many other geothermal areas around Iceland, water from the spring is also used to speed up the growth of plants and vegetables by heating up the surrounding greenhouses, and during the summer local farmers often set up stalls here to sell their produce to passing visitors. From the car park, a footpath leads to the spring; it’s wise not to get too close to the open pools of bubbling boiling water as it can, and does, splash over the protective fence in front. Incidentally, the area around the spring is the only place in Iceland where the unusual variety of hard fern, blechnum spicant, is found.