What Are They Hiding?

What dark secret is Google Earth hiding under the blanked out square in Hudson Bay?

Earlier I was zimming around the world in 80 seconds on Google Earth as I tend to do fairly often, peeking down on friends houses, revisiting favourite haunts, or just crusing. I zoomed down on Hudson Bay, Canada. Check it out. Just north of Churchill, just off the coast, there is a large blank space. What is the blank hiding? Some dark secret? Or just an error in the imaging software?

If anyone has any idea what is there, please drop me a line, I'd love to know.