Swim in the Blue Lagoon

The Blue Lagoon is basically a giant geothermal spa in the middle of an otherworldly lava field. The milky-blue water stays around 38°C (100°F) year-round, fed by the nearby Svartsengi power plant. Steam rises from the surface while you soak, surrounded by black volcanic rock.

The silica and minerals in the water are supposedly great for skin - there are even face mask stations around the lagoon. The contrast of hot water, cool air, and Icelandic landscapes makes it unlike any other swimming experience.

Located just 20 minutes from Keflavik airport, it's a popular first or last stop for Iceland visitors. The facility includes restaurants, a spa, and a hotel for those who want to stay longer.

Pro tip: Book in advance - walk-ins are rarely available. Condition your hair before entering (the silica is rough on it), and keep it out of the water if you can. Go during off-peak hours or in winter for smaller crowds. The Retreat Spa section costs more but is far less busy.