In early 2009, Hong Kong Disneyland proposed a financial arrangement to the Legislative Council of Hong Kong with the aim of expanding the park by adding three new themed areas. This plan was approved in July 2009. On 13 December 2009, the official groundbreaking ceremony took place.
The mountain, the centrepiece of the themed area, is 88 feet (27 m) tall tall and was constructed with 30 sculptors and 20 painters working on it for eight hours a day over a period of 14 months. The team visited California's Sierra Nevada Mountains and Yellowstone National Park before starting work. A town from the gold rush days of the 1840s and 1850s has been built around the mountain. Rocks on the mountain seem rough and eroded, but none of them are real. Instead, 3,850 tonnes of cement were used to create them. Even the bricks and "wooden" logs at the site are made from cement. The team used a special, relatively soft cement to shape the mountain's features. It is also structurally safer: the cement used to make the mountain is as strong as any cement used to build houses. To make the mountain look realistic, designers went through several exhaustive stages, including sketching, model-making, three-dimensional computer scans and adding authentic finishing touches. Two hundred people were hired in May 2012 to run Grizzly Gulch.
In June 2012, Big Grizzly Mountain Runaway Mine Cars began soft openings. On 14 July 2012, the ride was officially opened to the public.
Big Grizzly Mountain Runaway Mine Cars is the centrepiece attraction in the Grizzly Gulch section of Hong Kong Disneyland. It is a Vekoma Mine train roller coaster with 1,100 metres (3,600 ft) of track.
Legend has it that the mountain is home to not only a gold mine, but also to the 3 bears that led to its discovery. According to local lore, a resident by the name of Captain Cosgrove was out enjoying the mountain scenery when he noticed 3 bears scratching their backs on the craggy rocks. After the bears retired to their cave inside the mountain, the Captain suddenly noticed a sparkle in the rocks. The scratching had exposed gold underneath! Captain Cosgrove immediately staked his claim, and the Big Grizzly Mountain Mining Company was born.
Nobody is allowed to bother the bears—dubbed Rocky, Mother Lode and Nugget—because of the good fortune they brought to Grizzly Gulch. But the bears have been known to create a little havoc once in a while. It’s not uncommon to hear about a mine car that’s gotten loose because of something the bears unwittingly did... or to hear an unexpected explosion deep in the mountain. So prospectors are encouraged to beware: When the bears are hibernating, all is well. But when they wake up—look out! Anything can happen.
The ride begins in the Big Grizzly Mountain Mining Company building. Riders board one of several trains which seat 24 riders each. The train leaves the station and heads towards tunnel 8. A grizzly bear named Rocky uses a railswitch as a backscratcher and accidentally sends passengers down tunnel 4. In Chinese tradition, the number 8 signifies good luck and the number 4 signifies death, as the numbers are homonyms for characters representing luck and death, respectively. The train begins to climb a hill in the style of a traditional roller coaster. Once the train nears the top of the mountain the lift cable appears to break causing the riders to go back down the hill in reverse and along a different track before entering another mine. A mother bear and her cub, named Mother Lode and Nugget, are located inside the mine and one sets off some TNT when reaching for a miner's hanging catch of fish, causing the train to launch out of the mine on yet another track, similar to the Mine Car's TNT Explosion scene from the Walt Disney Animation Studios film Home on the Range. The train then goes through a variety of twists and turns before arriving at the terminal brake run and returning to the station, passing by Mother Lode and Nugget sitting in a blasted up mine-cart covered in fish.