IF YOU'RE LOOKING for something that will dazzle and entertain the whole family once the holiday hoopla is over, make your way to Baltimore. This week the National Aquarium there unwrapped its new $40 million Marine Mammal Pavilion.

From the outside, the new section appears to be identical to the original facility, but on the inside the look is totally different. While the older building -- with its low lights, dark carpeted walls and fluid music -- was designed to make visitors feel they were under the sea, the new building is bathed in sunlight from huge portholes, a soaring pyramid skylight and expansive windows. It gives you the feeling of being on the deck of a great ship. The differences are not merely for architectural interest; they're to dramatize the fact that marine mammals are not just another kind of fish.

Connecting the two sections is a glass-enclosed skywalk. As we made our way to the new building, my family and I were immersed in the taped songs and sounds of the humpback whale.

Once off the skywalk, we came face to face with Scylla the humpback whale. This life-size 45-foot sculpture is suspended from the ceiling and encompasses both levels of the new pavilion. Along the walkway surrounding Scylla are telescopes that provide a close-up view of various anatomical features of the whale, including her flippers, whiskers and blowhole. Hands-on exhibits show how whales breathe and how they cooperate to make "bubble nets" to trap fish for dinner.

After learning some basic facts about marine mammals from Scylla, it was time to see real ones in action. As the door swung open to the main attraction -- a 1.2 million gallon pool in a 1,300-seat amphitheater -- electrifying music filled the room.

While everyone waited for the 30-minute program to begin, we watched the dolphins (which we learned are a type of whale) through the large acrylic windows that surround the front of the 22-foot deep pool. These playful creatures worked the crowd as they dove and pressed their smiling faces to the windows. We soon realized that the dolphins were as interested in us as we were in them.

Two multi-screen video walls described how the marine mammals traveled to the aquarium and how some, weighing as much as 900 pounds, were hoisted into the pool with a crane.

As "Voices From the Sea: A Celebration of Whales" began, in walked two trainers, Doug Messinger and Doug Streepy, and the speaker, Duncan Whittier. At once, the dolphin stars -- Nalu, Nani and Akai -- gathered, ready to put on a show. Oohs and ahs echoed through the audience as Messinger, using hand signals, whistles and, of course, fish, instructed the animals to walk across the pool on their tails and leap out of the water in unison.

The dolphins then began doing double back flips and twists. While they were performing, pictures showing the dolphins doing similar acts in the open seas appeared on the video screens.

Whittier was quick to point out that most stunts the dolphins engage in during the show demonstrate a behavior that they perform naturally. And yes, this includes double back flips (although no one is quite sure why).

To show off their built-in sonar abilities, suction cups were placed over one dolphin's eyes while he retrieved plastic rings and brought them back to Messinger. Unfortunately for dolphins in the wild, their sonar can't detect drift nets.

And then it was on to some real fun. Doug dove into the water and Nani and Akai pushed him around the pool by his heels. Suddenly the dolphins crash-dived to the bottom of the pool with Doug still in front, only to zoom straight up, propelling him high into the air -- with the dolphins right behind. Now all that was left was for the dolphins to come to the front of the pool an take their bows. And that's just what they did.

Although nothing could top this show, we spent the remainder of our visit wandering through the discovery room. It's stocked with shark teeth, turtle shells and a chart where kids can find out how they measure up to a teenage great white shark.

Last it was on to the educational arcade with its computer games and plenty of buttons to push. Here we scored well on "Whales in Jeopardy." So I guess the aquarium had accomplished its mission. We were certainly entertained, but even more important, we had gained a better appreciation for marine mammals.

NATIONAL AQUARIUM in Baltimore. Pier 3, 501 East Pratt Street. 301/576-3810. Winter hours (effective Sept. 16 to May 14) are 10 to 5 daily (10 to 8 Fridays). Summer hours are 9 to 5 Monday through Thursday and 9 to 8 Friday through Sunday. Admission is $10.75 adults; $8.50 students (12 to 18), senior citizens and active duty military personnel; and $6.50 children 3 through 11 (younger free). Take I-95 north to the Inner Harbor exit in Baltimore, turn right on Conway Street, left on Light Street, right on Pratt Street and follow signs to the Aquarium.

TUESDAY -- The first 1,991 visitors will receive free admission to the aquarium. Visitors will be invited to decorate a special aquarium tree with conservation and recycling resolutions.

Alice Rindler Shapin last wrote for Weekend about local fan clubs.