Yet before you dip a toe into any potential balming or healing volcanic waters, the Blue Lagoon's location will take your breath away. This jewel in the crown offers a series of programmes for one-day visitors who make it part of a broader stay in Iceland. A so-called premium treatment at the Retreat Spa gains entrance to the lagoon, silica mud masks, drinks, algae masks, and a table reservation with sparkling wine and the tasting menu at Lava Restaurant. (The Retreat Spa also has its own restaurant, which features à la carte breakfast from 7.30am onwards as you gaze out at the mineral-rich waters and centuries-old lava.) The spa amenities are prodigious and include various in-water treatments, as well as massages in subterranean spaces.

Then there's Lava Restaurant – did we mention the view? Built into an 800-year-old lava cliff on the west bank of the Blue Lagoon, it's a place where the food couldn't be any more dynamic and enchanting; as an unforgettable culinary experience, this is second to none. Inspired by the Blue Lagoon's surrounding landscape and created by the chefs, the four-course taster showcases the savoury delights of Icelandic cuisine.