Oregon Zoo has debuted its new US$57m (€52.1m, £37.9m) Elephant Lands exhibit, concluding an eight-year journey to turn the vision into a reality.

Financed through a 2008 zoo bond measure and additional private funding, the new habitat is four times the size of the zoo’s previous enclosure, covering 24,000sq m (261,000sq ft), two thirds of which is accessible to the elephants.

Oregon-based SRG Partnership are behind the facility’s design, also acting as general contractor alongside Lease Crutcher Lewis and Equilibrium Engineers.

"We took 60 years of knowledge and information that we've gathered from working with elephants here and really put it into the design of this new habitat," said elephant curator, Bob Lee.

"It's filled with choice and variety. Lots of different topography. There's hillsides for them to run around. There's mud walls for them to play in. Massive pools for them to dunk themselves in. We couldn't be happier with all the work that's gone into it."

The new outdoor area has been described by the zoo as a “new era” for its inhabitants, with the space designed to promote animal welfare and herd socialisation, while connecting outdoor areas with communal indoor spaces.

The exhibit comprises several sections including the south habitat, north habitat and Forest Hall. Forest Hall, which opened to the elephants in May 2014, features natural light, an activity tree, and free passage for the animals. Connected to Forest Hall is a new elephant barn, replacing the existing building which was built in 1959.