A decade in the making, Denver's state-of-the-art aquarium--the largest between Chicago and Monterey, California--opened in 1999 but was struggling under a heavy load of debt in 2002, endangering its chances for long-term survival. Permanent exhibits include 14 aquatic habitats and re-creations of two ecosystems that are on opposite sides of the planet: the Colorado River in North America and the Kampar River in Indonesia. Both exhibits follow an indoor path that showcases the wildlife in and along each river, from their mountainous origins to their oceanic destinations. The Colorado River path features the greenback cutthroat trout (the Colorado state fish) as well as river otters and innumerable other aquatic denizens. It culminates in a flash-flood simulation and the 187,000-gallon Sea of Cortez display, populated with exotic fish and moray eels. The Kampar River path features endangered Sumatran tigers as well as the 320,000-gallon Depths of the Pacific exhibit, replete with sharks and reef fish. There is also a rotating exhibit space, which has featured temporary displays on shark, rays, and under-dock "lurkers," plus a restaurant, gift shop, and a soft sea-creature play area for children. Allow 2 hours.