Southern Mexico Section
My father's photographs revealed the location of Thor's belt in Central America and his hammer between Greenland and Norway. Zip doesn't understand how I can continue the search after Alister's murder, but I'm convinced this path also leads straight to those responsible. 
Lara's notes for the Mexico Expedition are as follows:
- The location of Thor's belt in Central America was easiest to pinpoint precisely on Odin's map, and I need it before I can use Thor's hammer anyway, so it's convenient to recover it first while Zip works on refining the precise location of Thor's hammer. Zip doesn't understand how I can continue the search after Alister's murder, but I'm convinced this path also leads straight to those responsible. And if Thor's hammer can indeed kill even the gods, then perhaps I will have the power to end Natla's immortal reign permanently. 
- Main article: Tomb Raider Underworld Story#Mexico
Directed to Southern Mexico by a photograph (taken by her father) of the desecrated wall map in Thailand, Lara explores Mayan ruins to find the entrance to Xibalba and, at the heart of the complex, another Proto-Norse temple. She encounters are carving that depicts a scene from Ragnarok (the Norse legend that tells of the "final battle of the gods" and ends with the flooding of the world), which relates Thor's pivotal battle with the Midgard Serpent. "Thor kills Jormungandr with his hammer, Mjolnir," reads Lara, "but then he retreats only nine steps before he succumbs to the serpent's venom." After draining Jormungandr's pool, she retrieves Megingjord - Thor's belt - and discovers that it powers his gauntlets.
- Tomb Raider Underworld, Southern Mexico loading screen
- Tomb Raider Underworld Journal Entry MEXICO EXPEDITION