Issyk Kul (also Ysyk Köl, Issyk-Kol: Kyrgyz: Ысык-Көл [ɯsɯqkœl]; Russian: Иссык-Куль) is an endorheic lake in the northern Tian Shan mountains in eastern Kyrgyzstan. It is the tenth largest lake in the world by volume (though not in surface area), and the second largest saline lake after the Caspian Sea. Although it is surrounded by snow-capped peaks, it never freezes; hence its name, which means "hot lake" in the Kyrgyz language (Chinese: 熱海; literally: "Hot Sea" in Chinese texts). The lake is a Ramsar site of globally significant biodiversity (Ramsar Site RDB Code 2KG001) and forms part of the Issyk-Kul Biosphere Reserve. It was the site of an ancient metropolis 2,500 years ago, and archaeological excavations are ongoing.
During the Soviet era, the lake became a popular vacation resort, with numerous sanatoria, boarding houses and vacation homes along its northern shore, many concentrated in and around the town of Cholpon-Ata. These fell on hard times after the break-up of the USSR, but now hotel complexes are being refurbished and simple private bed-and-breakfast pensions are being established for a new generation of health and leisure visitors.
The city of Karakol (formerly Przhevalsk, after the Russian explorer Przhevalsky who died there) is the administrative seat of Issyk Kul Province of Kyrgyzstan. It is near the east tip of the lake and is a good base for excursions into the surrounding area. Its small old core contains an impressive wooden mosque, built without metal nails by the Dungan people, and a wooden Orthodox church that was used as a stable during Soviet times (see state atheism).
Lake Issyk Kul was a stopover on the Silk Road, a land route for travelers from the Far East to Europe. Many historians believe that the lake was the point of origin for the Black Death that plagued Europe and Asia during the early and mid-14th century. The lake's status as a byway for travelers allowed the plague to spread across these continents via medieval merchants who unknowingly carried infested vermin along with them. A 14th-century Armenian monastery was found on the northeastern shores of the lake by retracing the steps of a medieval map used by Venetian merchants on the Silk Road.
The lake level was some 8 metres (26 ft) lower in medieval times. Divers have found the remains of submerged settlements in shallow areas around the lake. In December 2007, a report was released by a team of Kyrgyz historians, led by Vladimir Ploskikh, vice president of the Kyrgyz Academy of Sciences, that archaeologists have discovered the remains of a 2500-year-old advanced civilization at the bottom of the Lake. The data and artifacts obtained suggest that the ancient city was a metropolis in its time. The discovery consisted of formidable walls, some stretching for 500 metres (1,600 ft) and traces of a large city with an area of several square kilometers. Other findings included Scythian burial mounds eroded over the centuries by waves, and numerous well-preserved artifacts, including bronze battleaxes, arrowheads, self-sharpening daggers, objects discarded by smiths, casting molds, and a faceted gold bar that was a monetary unit of the time.
Articles identified as the world's oldest extant coins were also found underwater with gold wire rings used as small change and a large hexahedral goldpiece. Also found was a bronze cauldron with a level of craftsmanship that is today achieved by using an inert gas environment.
In 1916 the monastery at Issyk Kul was attacked by Kyrgyz rebels, and seven monks were killed.