Boybuloq (also known as Boy-Bulok and Boj-Bulok, , ) is a limestone cave in Uzbekistan, the deepest cave in Central Asia and all Asia except its western part. The cave is deep and long with the main entrance at an elevation of . It is situated at the edge of Baysun-Tau mountain ridge, the southern spur of the Gissar Range, in the southeast of the country. The nearest village is Dehibolo (Дюйбало in Russian), to the northeast of Boysun.
The cave developed in the covered karst of Upper and Middle Jurassic limestones, in monoclinal strata, in the preserved wing of an anticline. The thickness of limestone strata is from 200 to 350 meters. Contrary to most limestone caves it was not formed by water precipitation penetrating from the surface but, as the soluble rock is covered by insoluble strata, by condensation. Hence the cave consists mainly of very narrow passages which descend along the incident angle of strata, from time to time interrupted by vertical shafts, no deeper than , and ends with an impassable siphon.
It was explored by Russian cavers since 1984, in the framework of Ekaterinburg Speleo Club (SGS) and the Assoсiation of Ural speleologists (ASU), with the participation of cavers from Italy, Great Britain, Slovakia, France and Switzerland (in chronological order).
Naming
After the rain a small stream, a rarity in otherwise very arid mountain, flows from the cave entrance and it gave the cave a name. It is a composition of two words: boy buloq, which translates to rich spring in Uzbek language and the language of the people from the nearest village, the Tajiki.
Early history
The cave was known to local people since ancient times, because from its entrance a stream of water flows down the slope of the otherwise very arid mountain landscape. In the winter the village Dehibolo at an elevation of , its name translates to "the highest village", is cut off by the snow, and later in the summer the few springs, which provide water to residents, can dry up. In April 1971 Mustafo Zokirovič Holmominov (born 1917), a farmer from Dehibolo departed on a 4-hour trek to the cave (6 km) with his son Hudojberdi (born 1957) on two donkeys. The cave was known to him, he visited it several times before. The two reached the cave and Mustafo went into the cave to pray. After a crawl of about one hour, he reached the point close to the first shaft, where his kerosene lamp went out. In the darkness he missed the direction towards the entrance, and fell to his death into the abyss. Hudojberdi waited at the entrance for two days when the villagers from Dehibolo came and returned him home by force.
Young men from Dehibolo tried to find Mustafo in the cave on several occasions that summer and in the following years but to no avail. His remains were only discovered in 1985, during the first speleological exploration of the cave.
Exploration
After the discovery of Kiev Cave on the Kirk Tau plateau in Uzbekistan in 1972, 2340 m a. s. l., which was in the subsequent years explored to the depth of 990 m and was in the years 1977-1978 the deepest cave in the USSR, Russian speleologists from Ekaterinburg (SGS) in the late 1970s and early 1980s started to search for new deep caves in the wider area of the country. In May 1981 they discovered the Zindan cave (later renamed to Urals-Zenkov (Zindan) cave), 3100 m a. s. l., in the Ketmen'-Čapta ridge. Its spring at the elevation of 1300 m indicated the possibility of a very deep cave. Until January 1983 the final depth of 565 m was reached, in the siphon too narrow to dive. Several search expeditions in the summer 1983 were fruitless, while in 1984 a token SGS expedition to Khodja-Gur-Gur-Ata massif discovered a number of promising entrances.
During a larger expedition in 1985 a group of five expedition members was sent to Surkhan-Tau ridge to scout its surface for new caves. On the way, in the village Kurgancha, 1455 m a. s. l., they were told of a cave higher in the mountain, called Boybuloq into which a villager from the highest settlement in Uzbekistan, the village Dehibolo, went in 1971 and never returned. They followed the stream bed and discovered the low cave entrance, at an elevation of 2650 m. The cave began with 30 meters of a crawl, up to the throat in liquid mud, after which it was possible to stand up. A narrow meander followed, it slowly ascended for 600 meters in straight direction, to a height of 90 meters, where it turned down. Soon a 27 meter pit was reached and they discovered human bones at its bottom. They belonged to Mustafo Zokirovič Holmominov.