A new visitor attraction is set to launch later this year in Iceland in the shape of IceCave – a network of man-made tunnels and glaciers running inside the Langjökull Glacier.

Stretching back as far as 300m (984ft) into the solid ice glacier – the second-largest in Iceland – and a further 30m (98ft) below the surface, the ice cave will be one of the largest man-made structures in the world.

In the works since 2010, the US$2.5m (€2.1m, £1.6m) development will allow visitors to 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, 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 becomes the blue ice formed only under these specific conditions.

Backed by leading pension fund investors and the Icelandair Group, the project features an impressive raft of expertise, 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 is digging the man-made tunnels in the glacier.

Visitors will 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. Tours start in May and will last anywhere between 2.5 and 14 hours, dependent on tour package.