On top of being the cold­est and dri­est place on the plan­et, Antarc­ti­ca is home to a crim­­son-hued water­fall called Blood Falls that stark­ly pours down five sto­ries along an icy white glac­i­er. Sci­en­tists final­ly deter­mined that the gris­ly col­or comes from salty, iron-rich water from inside the glac­i­er oxi­diz­ing and rust­ing once it’s exposed to oxy­gen.