How did Erik take the money without actualling wetting it?!

Help, I'm confused! In the scene when Erik takes back the money he had paid Pony to take them to New Orleans, there is one thing I don't get. Considering that Erik had to swim to reach Pony's boat, how come he swam back without wetting the money? Not only I don't understand that but I also can't think of any way how could he possibly have done it. It would be impossible. The money would have gotten all wet and good for nothing even if he had carried it in his mouth.

«I was on the fire escape! I saw ya!»