Find Europe’s biggest hot spring, Deildartunguhver, about 5km west of Reykholt, just off Rte 50, near the junction with Rte 518. Look for billowing clouds of steam, which rise from scalding water bubbling from the ground (180L per second and 100°C). A brand-new bathing complex called Krauma offers sleek hot pools, a cold pool and two steam rooms. There's also a restaurant.

A take-and-pay tomato stall is usually set up in the parking lot – the tomatoes are grown in a nearby greenhouse that harnesses the spring’s energy. Also, look for the rare Blechnum Spicant fern, only found here. The closest bus, Strætó 81, stops at Kleppjárnsreykir, 3km away.