You look up and see, inches away, the grim jaws of a sevengill shark. Flail and scream? Calmly pass out? Not if you're at UnderWater World, San Francisco's new $40 million state-of-the-art aquarium. (Otherwise, start panicking.) Moving sidewalks take you on a tour through 300 feet of transparent underwater tunnels, where you can observe up close -- and without getting wet -- the indigenous fish and natural habitats of San Francisco Bay.

The first such aquarium in the United States (the original is in New Zealand), San Francisco's UnderWater World features more than 10,000 creatures.  The tanks are full of spiny dogfish and bloopy moon jellies, flowery sea anemones and bristly sturgeons, clinging bivalves and razor-thin bat rays. But it's the sharks that steal the show. Eric the Shark Expert, his voice deeper than the sea, welcomes you to Shark Country. Spotted leopard sharks swim gracefully past as Eric reports that sharks can smell a single drop of blood diluted in a billion parts of water. Eager as a great white, the kids eat it up, and learn a little about marine life while they're at it.

UnderWater World, Pier 39, (415) 623-5300.