One of the largest man-made structures in the world has opened inside Iceland’s Langjökull Glacier in the shape of IceCave – a development designed for visitors to see the naturally occurring blue ice phenomenon.

Backed by leading pension fund investors and the Icelandair Group, the network of man-made tunnels stretches back as far as 300m (984ft) into the solid ice glacier – the second-largest in Iceland – and a further 30m (98ft) below the surface.

In the works since 2010, the the US$2.5m (€2.1m, £1.6m) IceCave includes an impressive list of experts who worked to make the project a reality, including one of Iceland’s leading geophysicists and glacial experts, Ari Trausti, plus a team of specialist construction workers. Iceland-based engineering and consulting company EFLA dug the glacier’s tunnels.

Visitors from across the world can now see blue ice. Each year, the ice cap is covered in roughly six metres of fresh snow, which on one side is compacted by the weight of the snow, and on the other, is melted by the warmth from the sun. That compacted snow turns to ice, which over time becomes denser until it eventually forms blue ice, only seen under these specific conditions.

Once operating under a full calendar, visitors can embark on a weather-dependent adventure between March and October on an ex-NATO, eight-wheel drive missile launcher, converted and adapted to transport up to 40 people at a time to the glacier. Depending on the tour, the experience will last anywhere between 2.5 and 14 hours.