The Aquarium at the Silverton Hotel

The lobby of the Silverton holds what might be the best free animal exhibit in Las Vegas: a 117,000-gallon saltwater reef tank stocked with thousands of tropical fish, three species of stingray, and three kinds of shark. This isn't a decorative fishbowl - it's a floor-to-ceiling acrylic wall with real coral structure, and there's enough life in the water that something is always cruising past the glass. Thursday through Sunday, costumed mermaids swim among the fish about every half hour, waving and posing for photos with kids pressed up against the acrylic.

The honest catch is geography. Silverton sits off I-15 at Blue Diamond Road, a 10-to-15-minute drive southwest of the Strip, so you're making a trip, not taking a detour on foot. It earns the drive if you time it: stingray feedings run daily at 1:30 and 4:30 PM, and the mermaids take a hard break from 3:45 to 5:00 PM, when the tank goes back to just fish. There's more water than the big tank, too: 500-gallon jellyfish tanks at the Mermaid Lounge and an 18,000-gallon koi tank in the attached Bass Pro Shops. Chain those together and you've got a solid free hour; the aquarium alone is a 20-minute stop.