Did you know there are giant freshwater lakes under Antartica's surface?

Of these, Lake Vostok is the largest and most well-known:

http://en.wikipedia.org/wiki/Lake_Vostok

Because the lakes are isolated from the surface by the ice, they've become a unique and extreme environment for the development of microbes separated from the rest of the world.  A deep ice core sample was taken from Vostok in order to study the microbes.