Rogue did a little exploration of the Atlantis level and decided she wanted to search around without any water. You heard me. No water.
Notice how Rogue is flying here, there is no water, and the rest of the characters are standing around with their idle poses.
Cyclops is wondering why this woman is still swimming when there is no water.
Psylocke discovers when she enters a new area, the water comes back... bummer.
I love being able to fly around in the sky boxes and explore the levels the way you weren't meant to.