Mt. Erebus is at the end of our world — and offers a portal to another.It's our planet's southernmost active volcano, reaching 12,448 feet (3,794 meters) above Ross Island in Antarctica. Temperatures at the surface are well below freezing most of the year, but that doesn't stop visits from scientists: Erebus is also one of the few volcanoes in the world with an exposed lava lake. You can peer over the lip of its main crater and stare straight into it.