Vatnshellir Lava Cave: 8,000 Years Old, 35 Metres Down

The drive from Reykjavík

The cave sits 136 km from Reykjavík, a two-hour drive if the weather leaves you alone. You take Route 1 north out of the city, cross under Hvalfjörður in the tunnel, then turn west onto Route 54 at Borgarnes and follow it the length of the Snæfellsnes peninsula. At the western tip Route 54 becomes Route 574, the loop around Snæfellsjökull, and the cave car park is signposted off it.

Nobody drives to Vatnshellir and nothing else. The turn-off sits between the Lóndrangar basalt pillars and the black pebble beach at Djúpalónssandur, ten minutes west of Arnarstapi and about 25 minutes south of Hellissandur, which puts it in the middle of a full peninsula day rather than at the end of one.

What the car park looks like

There is no visitor centre and no ticket office. The entrance is a small rusted metal hut over a hole in the lava field, a few minutes' walk from a gravel car park, and your guide arrives with the helmets in the back of a vehicle. Arrive 10 minutes before the time printed on your ticket, because the group goes down together and the hatch is locked behind you.

There are no toilets at the cave. The nearest are at the Malarrif visitor centre, about three minutes further along Route 574, and that is also where the national park rangers sit if you have questions about the rest of the peninsula.

• Gravel car park, free, room for perhaps fifteen cars in high summer
• No shelter: in a westerly you wait in the wind or in your car
• Route 574 is paved the whole way, but wind closes it to high-sided vehicles
• Nearest fuel is at Hellissandur or Arnarstapi, both around 25 minutes away
• Nearest toilets and drinking water: Malarrif visitor centre, three minutes east

Staying on the path

The lava field around the hatch is covered in woolly fringe moss, and a footprint in it stays visible for decades. Walking off the marked path is prohibited inside Snæfellsjökull National Park, and the rangers do enforce it. Keep to the gravel between the car park and the dome, which is all of ninety seconds anyway.

The two staircases

Your guide unlocks the hatch and hands out a helmet and a torch. The first spiral staircase takes you through the roof of the tube into the upper section, and the second drops you from there into the lower chambers. Both are steel, both turn tightly around a central post, and climbing them unaided is the real requirement of this tour. The walking is short. The stairs are what people underestimate.

Below the second staircase the route runs through three chambers to the deepest point, 35 metres under the surface. The tube is about 200 metres long in total, which means you cover the ground slowly and stop often rather than march.

• Helmet and torch handed out at the hatch, included in every ticket
• Two spiral staircases, one at the entrance and one between levels
• Three chambers on two levels, the lowest at 35 metres
• Your own headlamp is not allowed inside, so leave it in the car
• The floor is bare lava rock: uneven, dry in places, slick in others

Why the rock is red, yellow and green

The colours on the walls are minerals left behind as the tube cooled. Iron reads as rust red, sulphur as pale yellow, copper as green, and the guide will put a torch beam on each so you can see the difference. Along the upper section the lava froze into shapes as it drained, which is where the cave gets the lava statues the operator talks about.

At the deepest point the guide asks everyone to switch their torches off. In total darkness the cave is silent enough that people start to hear their own pulse, and it is the part of the tour that shows up most often in reviews.

What to wear for a cave just above freezing

The temperature underground sits a few degrees above freezing all year, somewhere around 4 to 6°C, and it does not change in July. The walls are unlit and the air is damp. A fleece and a windproof layer are enough, gloves matter more than people expect because you hold a cold steel handrail for two staircases, and your shoes need a grip.

Summit Adventure Guides refuses high heels, flat-soled shoes and flip-flops at the entrance, and that is not a formality: the floor was never levelled. Hiking boots are ideal, trainers with tread are accepted.

The Purkhólar eruption, 8,000 years ago

The lava that built Vatnshellir came out of the Purkhólar crater row on the lower slopes of Snæfellsjökull. Molten rock ran downhill in a river, the surface of that river cooled and hardened into a roof, and the lava underneath kept flowing beneath it. When the eruption stopped, the last of the melt drained downhill and left the roofed channel standing empty. That empty channel is the cave.

The date puts Vatnshellir in a different class from Iceland's other visitable caves. It drained roughly 8,000 years ago, which makes it around 3,000 years older than Raufarhólshellir and some seven thousand years older than Víðgelmir, formed in the Hallmundarhraun eruption around 900 AD. Older rock means more time for water to carry iron, sulphur and copper into the walls, which is why the colours here are stronger than the age of the lava would suggest.

A water cave with no water

Vatnshellir translates from Icelandic as water cave, which puzzles most visitors, because the floor is dry. The name comes from the farm and the water source it sat near rather than anything inside, and the tube itself never carried a river. Rain does find its way through the rock in places, so expect a few damp patches on the lower level.

Locked until 2011

The cave was known for a long time before anyone could walk into it. Cavers went down on ropes; everyone else stayed on the surface. The staircases and the hatch went in and the cave opened to the public with guided tours in summer 2011, and Summit Adventure Guides has held the licence since.

The mountain above has a longer literary record than the cave below. Jules Verne sent his characters down through Snæfellsjökull in Journey to the Center of the Earth in 1864, and the operator leans on the line hard enough that the tour is often sold as the first steps of that descent. Verne never came to Iceland.