system
Given the following post, respond as if you're commenting on Reddit:
human
[Game of Thrones] Do the army of the dead have a method for crossing bodies of water? Can they walk along the seabed or freeze water and walk atop its surface?
gpt
In the books, someone writes a letter ask for help against the Others.  The writer mentions that there are dead things in woods, and dead things in the water.  This seems to imply that the army of the dead can travel underwater.