Construction of a US$400m (£262m, €359m) theme park and leisure complex is progressing quickly in the popular Vietnamese destination of Halong Bay.

The 140-hectare (345 acre) project has been conceptualised and masterplanned by leisure consulting company International Theme Park Services (ITPS). ITPS collaborated with Wyatt Design Group and Hetzel Design on different aspects of the project.

The project, dubbed Vietnam Ocean Park, is being built on mainly reclaimed land overlooking the beachfront of Halong Bay – an area famed for its stunning limestone karsts and turquoise waters and a UNESCO World Heritage Site.

“It’s a beautiful part of the world, which sees about 10 million visitors per year – a number that continues to grow,” ITPS president Dennis Speigel told Attractions Management.

“This will be one of the major theme parks in that part of the world,” Speigel said. “And it’s one of the most intense projects we’ve ever worked on as we designed this multi-faceted project in just nine months. In my 47 years, I’ve never seen a project so quickly designed, developed and constructed.”

Ocean Park is being built by Da Nang-based Sun Group Corporation, one of Vietnam’s leading hotel and theme park developers. Parts of the Ocean Park will open by the end of this year, with the next phases in 2016 and 2017.

The development will include a theme park, a waterpark, a mountaintop FEC and 115-metre (377-foot) giant wheel, a beachfront village, global showcase and resort accommodation. Theming is inspired by the heritage of and mythology of Halong Bay and Vietnam. The design will recreate local turn-of-the-century architecture and is pitched to attract both Vietnamese and foreign tourists.

Spiegel said that the development, which is costing between US$300m (£196m, €268m) and $400m, will also boast the world’s longest free span double-decker cable car, connecting Ocean Park on the mainland to a “Mystic Mountain” in the bay.

The theme park itself will measure approximately 25 hectares (62 acres), with about 30 rides and attractions, including thrill rides and family rides. The 9-hectare (12-acre) waterpark will have a variety of thrill slides, family slides and pools.