Cave Explorer Drops Rock in World's Deepest Cave

A video has gone viral showing a caver dropping a large rock into the deepest section of what's known as the world's second deepest cave, triggering an unusual "test" with spectacular results.

The video appears to have been recorded in Veryovkina Cave (also known as Verëvkina Cave), a cave in Abkhazia. With a depth of 2,209 meters (7,247 feet), it's the second deepest known cave on Earth. This eerie place is located in Veryovkina, within the Arabika Massif of the Western Caucasus' Gagra Mountain Range, on the pass between Krepost and Zont mountains, near the slopes of Mount Krepost. Its entrance sits at 2,285 meters (7,497 feet) above sea level.

Some people online have pointed out that in the recording, it took nearly 16 seconds for the rock to hit the bottom. Applying the equation speed = distance/time, the approximate fall was only 157 meters, not the 2,000+ meters claimed. However, it's also important to remember that there's a delay between when the rock hits the bottom and when the sound is heard, as sound also takes time to travel.