World's deepest, largest underground lab opened

A 2.4-kilometer-deep physics laboratory in Southwest China's Sichuan province became operational on Thursday, making it the deepest and largest underground lab in the world.

Scientists believe the laboratory provides a "clean" space for them to pursue the invisible substance known as dark matter. They said the extreme depth helps block most cosmic rays that mess with observations.

The Deep Underground and Ultra-low Radiation Background Facility for Frontier Physics Experiments (DURF) is located beneath Jinping Mountain in Sichuan's Liangshan Yi autonomous prefecture.