Xakk
Eye of Cthulhu
You don't have to go through the sand if you have a clentaminator. A sweep from above and another from below should touch all the sand.Still got to dig through all that sand ... ><
Suppose I can line the ocean floor with obsidian or something non-corruptible ... then fill my inventory with corrupted sand ... not sure where to do go from there.
Build a base in the sky to dump the sand for cleaning then put it all back?
Edit: AH!!! It's hopeless. There are altars under the seabed ... might as well try to move Everest by digging at it with a spoon.