You don't actually have to go to the National Aquarium to watch its hypnotizing jellyfish undulate through the water. The striking jellyfish are so enthralling that the aquarium had a live webcam pointed at them 24/7. Of course, it's more exciting to see them in person—and you can also ogle the giant northern sea nettle, a 10-foot jellyfish, and the totally translucent moon jelly while you're at it.
Nearby at the aquarium, you'll stumble upon Shark Alley. It's home to sandbar and sand tiger sharks, roughtail stingrays, and the large-tooth sawfish. After exploring the Alley, check out the Amazon River Forest, rife with neon boa constrictors and massive river turtles. Head to the Dolphin Discovery area, where you might get to see Bayley or Beau, two of the dolphins living at the aquarium. There's much more to experience at the National Aquarium, so make sure to carve out an entire day to explore.