What is the Door to the Underworld, and where is it?

The Batagaika Crater in Siberia, a massive thermokarst formation, is expanding due to thawing permafrost, revealing ancient geological and biological records. This \"Door to the Underworld\" serves as a critical natural laboratory, offering insights into Earth's past climate and acting as a stark warning of accelerating permafrost melt driven by climate change and past deforestation.