You can purchase tickets at the door but we highly suggest you order them online and skip the long lines that often form. In addition, they get really busy and we recommend that you visit very early in the morning or after 4pm in the afternoon and try to visit them during the weekdays if you can.
In addition to the marine life you can get up close and personal with several species of birds: puffin, finch, lorikeet, macaw, parrot and several others who call the Baltimore Aquarium home.
We took the family one afternoon and really enjoyed ourselves. We were able to get up close and personal with many of the animals on display and we took our time going through all of the exhibits that we wanted to see. You will do a lot of walking and it was very crowded on the day that we visited. You will want to plan ahead if you can!
You can learn more about the National Aquarium in Baltimore at Inner Harbor by visiting their site online. In our honest opinion, it is definitely one of the nicest...if not the nicest aquarium to visit here in the northeast and middle Atlantic states.