is 18% vacant. Nickelodeon Universe is an indoor theme park in the center of the mall. The park features roller coasters , among numerous other rides and attractions, and is the largest indoor theme park in the United States . Unlike many indoor amusement parks, Nickelodeon Universe has a great deal of natural foliage in and about the park, and its floor has a wide variance in height - the highest ground level in the park is 15 feet (4.6 m) above the lowest. The park features two new roller coasters, SpongeBob SquarePants Rock Bottom Plunge and Avatar Airbender , and a new thrill ride called BrainSurge . The latter roller coaster bills itself as a "rather peculiar" ride. It also has a miniature golfing section called Moose Mountain. This miniature golf course features eighteen holes and a relatively fast astroturf surface. MOA has partnered with EMS Entertainment to open a permanent exhibits space on the third floor of the old Bloomingdale's space on the southeast corner of the mall that will host exhibitions of different kinds. There is space for three exhibits at a time with one larger exhibit space and two smaller ones. The first exhibit to open is Barbie: The Dreamhouse Experience , which opened to the public on February 14, 2014 [ 27 ] and will remain open for two to three years. Visitors tour Barbie's dreamhouse, try on clothes in her virtual closet, make virtual cupcakes in Barbie's kitchen, have their photo taken by "Selfie