Those aren't underground jellyfish, they are underwater. That part of the word (...

dstorrs on Sept 20, 2012 | parent | context | favorite | on: Xkcd "Click and Drag" in a "map" interface

Those aren't underground jellyfish, they are underwater. That part of the word (west of center, where the ships are) is ocean. But yeah, it's confusing at first.