World's Largest Underground Room: Miao Room, China

The largest known underground chamber by volume is the **Miao Room (Miao Keng)** in **Gebihe Cave System, Ziyun County, Guizhou Province, China**. Discovered and laser-scanned in 2013 by an international team (including British, Chinese, American cavers):

• Volume: ~10.78 million m³ (380 million ft³)
• Dimensions: ~852 m long, ~190 m wide, ~270 m high at tallest.
• Area: ~150,000 m² floor area.

Previous record-holder: **Sarawak Chamber** (Gua Nasib Bagus, Gunung Mulu National Park, Borneo, Malaysia) – ~9.5M m³. **Mammoth Cave** (Kentucky, USA) is the **longest cave system** (675+ km surveyed) but its largest room (Mammoth Dome / Chief City) is smaller (~1.5M m³). Miao Room's discovery redefined "largest chamber" metrics using 3D laser scanning.