The mineral waters of "Proval" Lake in Pyatigorsk captivate visitors with their vivid turquoise hue, a result of high sulfur content and the presence of specific bacteria. The water temperature ranges from 26°C to 42°C. In 1858, a tunnel was carved through the mountain to access the lake, and in 2008, a monument to the famous literary character Ostap Bender was erected at the entrance. Visitors are free to take pictures with the monument, though they might have to queue with others. The water level in the lake is not constant and can fluctuate. However, swimming in the lake has been off-limits for several years, as the area is fenced off with a metal barrier.