Denver’s state-of-the-art aquarium—the largest between Chicago and Monterey, California—opened in 1999 as a nonprofit, went belly-up, and in 2003 was sold to the for-profit Landry’s seafood restaurant chain. The sale brought the aquarium stability, not to mention new exhibits and a theme restaurant and lounge on-site. Residents include greenback cutthroat trout (the Colorado state fish), river otters, nurse sharks, sea turtles, and moray eels swimming in 1 million of gallons of water here. At “Stingray Reef,” visitors can pet and feed the slippery denizens. On Saturdays, divers and novices can swim in the big tanks for a fee ($185 for divers, $85 for snorkelers). Allow 2 hours.