The New Athos Cave (Georgian: ახალი ათონის მღვიმე), also Novoafonskaya, Novy Afon Cave, or New Afon Cave) is a karst cave in the Iverian Mountain, Georgia near New Athos. It is one of the largest caves in the world with the volume of its void of about 1,000,000 m3.

The abyss on a slope of the Iveran Mountain was known for ages, referred to as the "Bottomless Pit". It was explored in 1961 by an expedition of four: Zurab Tintilozov, Arsen Okrojanashvili, Boris Gergedava, and Givi Smyr.

Since 1975 it is a tourist attraction in Georgia, featuring its own underground railway. The cave consists of 9 major cavities.

credited to wikipedia