Midgard

In mythology, the Midgard is a huge serpent daughter of Loki and the main rival of Thor and is said to circle the globe on the sea floor. In the game it is actually a huge and ancient device of unknown origin built in Helheim to hit the atlantic fault, the weakest part of the earths crust. as the atlantic fualt circles the earth on the sea floor this is most likely how the myth came about. According to Amanda, the device has the power to tear the world apart. In the final level, Natla activates the device, but Lara is able to destabilize it, causing it to shake. Natla then attempts to restabilize it, but is prevented as Lara throws Thor's Hammer at her, causing her to fall into the void pit, problably dead(though judging on how natla continually comes back this may not be the case as her death was not confirmed). The machine is then destroyed as the void pool starts to flood the cave. Both Lara and Amanda are able to escape from there, using the Stone Dais located near of there.