Guide de Voyage : Neptune Ice Cave

Glacier truck on Langjökull

The Neptune Ice Cave is a natural ice cave inside Langjökull, Iceland's second-largest glacier, in the western Highlands north of Gullfoss waterfall. It was found by glacier guides in October 2025 and opened to visitors for the 2025–26 winter season, reached from the upper Gullfoss car park in purpose-built glacier trucks.

The name is English rather than Icelandic: the guides who found it named it for the deep blue of its ice, which they compared to Neptune topaz. Langjökull itself means "long glacier", a fair description of an ice cap roughly 50 km long and 15 to 20 km wide.

Key Takeaways About Langjökull

• The Neptune Ice Cave is a natural meltwater cave inside Langjökull, found in October 2025 and opened for the 2025–26 winter.
• It can only be visited on guided tours, which meet at the upper Gullfoss car park (about 120 km from Reykjavík) and use glacier trucks.
• Ice cave tours run from November to mid April; the cave changes every winter and may be replaced by a new cave in later seasons.
• Crampons are provided; minimum age 4 on the truck tour; dress for a glacier in winter.
• Not to be confused with the man-made Langjökull ice tunnel reached from Húsafell on the west side of the glacier.

Why visit the Neptune Ice Cave

Most of Iceland's famous ice caves are in the south-east, on the outlet glaciers of Vatnajökull, a long day's drive from Reykjavík. The Neptune Ice Cave sits on the Golden Circle side of the country and can be combined with Gullfoss and Geysir in a single day.

It is also a natural cave, not a tunnel. Meltwater running under and through the glacier in summer carves a channel; when winter freezes the water, the empty channel becomes a cave that is stable enough to walk into.

Guides describe Neptune as spacious, with high-clarity blue ice and thin layers of dark volcanic ash trapped between the ice layers, a record of eruptions that dusted the glacier in past centuries. The blue comes from dense, old glacier ice that absorbs red light and lets blue through.

Langjökull covers roughly 900 square kilometres and its ice is up to about 580 m thick. The glacier is retreating: its outlet tongues reached Hvítárvatn until around 1900 and have pulled back rapidly since. A natural cave like Neptune is temporary.

It changes shape through the winter and melts out or collapses in spring, so the cave you walk through may not exist in the same form next year.

The journey is part of the attraction. From Gullfoss the route climbs through the Highlands with views over the lake Hvítárvatn and the Jarlhettur peaks, in trucks built for the ice; Sleipnir Tours' Tatra-based 8x8 trucks run on 65- and 78-inch tyres, weigh about 26 tonnes and seat 47.

How to get to the Neptune Ice Cave

There is no public road onto Langjökull and the cave cannot be visited independently. Every visit is a guided tour that departs from Gullfoss.

• Meeting point: the upper Gullfoss car park, off Route 35 (Biskupstungnabraut). Gullfoss is about 120 km from Reykjavík, roughly 1 hour 45 minutes to 2 hours by car via Route 1, Route 35 and Route 37, or Route 35 all the way through Skálholt.
• Nearest town: Reykholt in Biskupstungur and Flúðir, both within about 35 km, have fuel, shops and accommodation.
• On the tour: passengers board a glacier truck or transfer bus at Gullfoss and drive to the Geldingafell base camp at the south-east edge of the glacier, then continue onto the ice. The glacier truck tour takes about 4 hours in total; a longer version from Reykjavík adds the Golden Circle sights. Other operators reach the cave by snowmobile from base camps near Gullfoss.
• Walking: the walk from the truck to the cave entrance is short, but the cave floor is uneven ice with narrow steps. Crampons are provided and fitted before you go in.
• Parking: free at Gullfoss at the time of writing. A normal 2WD car is fine in winter as far as Gullfoss, though Route 35 can be icy; check road.is before setting out.

Best time to visit

The cave is open only in winter, when the meltwater that formed it is frozen. Sleipnir Tours runs ice cave tours from 1 November to 15 April; in summer (16 April to 31 October) the same trucks run glacier tours without a cave visit.

December to February gives a chance of northern lights but also the shortest days and the most weather disruption; March and early April have long daylight and generally easier roads. Guides assess the cave before each visit and decide the route accordingly.

Operators search the glacier for the best natural cave each autumn, so tours from November 2026 may visit a new cave rather than Neptune.

Safety and practical tips

• Dress for a glacier in winter: warm layers, waterproof shell, hat, gloves and sturdy ankle-high boots. Crampons go over your own boots.
• Storms close the glacier; book early in your trip so a cancelled tour can be rebooked.
• The glacier truck tour has a minimum age of 4, though the operator suggests 6 and up is more practical; snowmobile versions have higher age limits and require a driving licence to drive.
• The cave is checked by the guides. Stay with your guide and do not touch or lean on the walls; the ice is harder than it looks and sharp where it has fractured.
• Toilets, a café and a shop are at the Gullfoss visitor centre; the larger trucks also carry a toilet.