A lava cave tour in Iceland

Inside, the route follows a footbridge over the roughest rock, and lighting along this part of the tunnel brings out the changing colors of the walls. The guide explains the geological formations as you go, and at one point switches off the lights so you can feel complete darkness underground.

The air inside is cold and damp, around 0 to 4 °C, with water dripping from the ceiling, so dress warmly whatever the season. The ticket covers the guided walk, the helmet and headlamp and, in winter, crampons; gratuities are not included. You can reserve now, pay later, and cancel free of charge up to 24 hours before.

It is big for a lava cave. The operator gives a total length of 1360 m, with the main tunnel 900 m long, a width of up to 30 m and headroom of up to 10 m. Visit South Iceland calls it the largest of the many caves in the lava fields of Ölfus. Standing in the main passage, the scale is the first thing you notice.

Near the entrance the ceiling has caved in and created three columns of light inside the tunnel. At the far end, beyond the reach of the standard walk, the tube splits into three smaller tunnels with lava falls. The hour on the footbridge covers the part that is easily accessible for most people.

The route gets praise too. Guests mention good trails and ramps, a well-lit tunnel and the hard hat with a headlamp handed out at the start. One reviewer notes that the tunnel was wide and high in most areas, and that even a claustrophobic traveler in the group had no trouble.

The criticisms are useful. One guest found the turn-off easy to miss on the first pass and wished there were coffee or food on site, and the same guest recommends clothes that cope with water, since it rains inside the tunnel all year. A Spanish visitor would have liked some explanation in Spanish; the guide on this listing speaks English.

Winter is the dramatic season. Every winter, ice sculptures form inside the entrance of the cave, the operator says, and snow builds white mounds under the skylights. The listing includes crampons in winter for the frozen stretch near the entrance. Outside, the days are short: at mid-month in December the sun is up for only 4.4 hours.

Summer brings the opposite. By mid-June the sun stays up for 20.8 hours a day, and the light shafts near the entrance stay bright late into the evening. Inside, nothing changes: the tunnel keeps its cold, damp air whatever the month, so the same warm layers belong in your bag in July as in January.

The road crosses an open lava heath where the weather can change quickly. Visit South Iceland lists road conditions on tel. 1777 and at road.is, and advises being prepared for quickly changing conditions in every season. In winter, check before you set off and leave extra time for an icy parking lot.

Without a car, other listings add a coach from Reykjavík to the same guided walk. One drives 40 minutes each way and starts from $68; the walk sold here meets you at the cave instead, so it suits travelers with their own wheels. Both end at the same footbridge in the same tunnel.

The operator also lets you attend a different departure than the one you booked, as long as there is availability. If you are running late, ask the staff on site about the next departure rather than assuming there is space, especially in the busy summer weeks.

Prices on this page load live from GetYourGuide and convert into your currency. The walk starts from $72, and the final amount depends on your date and the number of people. Gratuities for the guide are not part of the price, so bring a little extra if you want to tip after a good hour underground.

Further in, the lighting along the footbridge brings out the reds, oranges and greys of the walls. Stand still, brace your phone against a railing and take a few frames: low light needs a steady hand. Keep a cloth in your pocket, because water drips from the ceiling and fogs or spots the lens.

Do not try to photograph the moment of total darkness. When the guide turns off the lights, the point is to experience it, not to light it up again with a screen. And keep your hands and tripod off the formations: the operator writes that stalactites disappeared from the tunnel after visitors started arriving in numbers in the 1950s.

Think in layers. Visit South Iceland calls layering the key to dressing well in Iceland at any time of year, with wool close to the body and a wind- and waterproof shell on top. A beanie thin enough to wear under a helmet, plus gloves for the cold railings, completes the outfit for a cave near freezing.

Winter needs a little more for the trip there and back. Visit South Iceland recommends an insulated jacket with ice cleats, ice grips or anti-slip soles. Inside the cave, the crampons in the listing take care of the icy entrance. Leave smooth city soles at the hotel, whatever the season.

Groups on the standard tour can be sizeable. The operator says the standard group is usually up to 30 passengers. A solo traveler can book too: the tour runs even with one person, though you will likely join others booked on the same slot. Sharing the hour with other curious visitors keeps the questions coming.

If you want more time with a guide, the operator's Lava Falls Adventure Tour goes beyond the footbridge to the end of the tunnel, in small groups with a designated caving guide. It takes 3 to 4 hours, has an age limit of 12 and needs hiking boots with ankle support.

Further west, Vatnshellir on Snæfellsnes is an 8,000-year-old lava tube visited only on guided tours, on a 45-minute tour that goes down two spiral staircases. Víðgelmir in Hallmundarhraun, which its operator calls Iceland's largest lava cave, is toured on a walkway in 1.5 hours.

Each cave has its own character: the lit breadth of Raufarhólshellir, the vertical descent of Vatnshellir, the size of Víðgelmir and the raw rock of Arnarker. The guides on this site set them side by side, with listings, prices and requirements for each cave, so you can pick the one, or the two, that suit your route.

It is not an adventure in the caving sense: you stay on a lit route, and the deep end of the cave is left for the longer tour. If you want to scramble over boulders, look at the Lava Falls trip or at Arnarker instead. If you want an hour of real geology, an easy route and a moment of total darkness, this is the right choice.

Last, the honest caveat about comfort: it is cold and it drips, around 0 to 4 °C, all year. Dressed properly, that is part of the fun. Dressed for a café, the hour will feel long. Bring layers, a waterproof jacket and sturdy shoes, and the cave will be one of the most memorable hours of your trip.