20 Out-Worldly Places On Earth That Look So Unrealistic, But They Aren't

This world is uncanny! The more you discover it, the more amazing it turns out to be. And the gems it holds within it, some of them are just so unbelievable, they look like they belong to another planet.

Son Doong Cave, Vietnam: The biggest cave on the planet when measured by cross-section. Discovered and explored for the first time in 2009. Only open to the public since 2013. Unique for the two enormous dolines (cave roof collapses) and underground rainforests. Home to the "Great Wall of Vietnam," a 90m high calcite barrier.