Danish architecture studio BIG has revealed new images by Rasmus Hjortshøj of Marsk Tower, its spiralling double-helix viewing tower that recently opened to the public in southwestern Denmark.

The 25-metre-tower is located in the UNESCO world heritage site of Wadden Sea National Park and was constructed from Corten steel.

"Marsk tower is a testament to our two-decades-long friendship and collaboration with the blacksmiths of Schacks Trapper," said BIG founder Bjarke Ingels.

"The double helix provides two stairs and an elevator with a single stack of rotating steel steps, allowing visitors to ascend and descend in a single spiraling loop from the sand to the sky – connecting the marshland to the Wadden Sea.”

The tower is topped by a viewing platform and will provide 360-degree views across the marshland from which it is named – "marsk" is Danish for marsh.

"Because of the earth curvature, visitors will gradually expand their view of the horizon while walking to the top of the tower," BIG partner Jakob Lange said.

"On the foot of the tower, you will be able to see four kilometres into the distance, but from the top of the tower the view is expanded to an 18-kilometre view into the horizon."

As well as a lookout tower, the building was designed to function as a tourist landmark. Reaching a height of 36 metres above sea level in the flat landscape, Marsk Tower will be visible from afar.

An elevator at the core of the 146-step tower provides access for wheelchair users.

The structure was created for Marsk Camp, a tourist destination that aims to showcase the unique landscape of southern Jutland.

The Wadden Sea area where the building is located was given UNESCO world heritage status as the largest unbroken system of intertidal sand and mudflats in the world.

The tower was designed to have a "natural aesthetic" that would blend in with these surroundings.

"Our ambition is to elevate Southern Jutland’s tourism experience to a new level and present this unique landscape from a new perspective to tourists from all over the world," said Marsk Camp's Jørgen Hansen.

BIG, founded by Bjarke Ingels, is one of the world's best-known architecture studios and has designed numerous sculptural buildings.

The studio recently unveiled visuals for a Swedish travel center with a curved timber ceiling, and chose a looping design for the O-Tower skyscraper in Hangzhou, China.

Photography is by Rasmus Hjortshøj.