Lake Issyk-Kul (Ozero Issyk-Kyl in Russian), a drainless lake in the northern Tien Shan (mountains) of Kyrgyzstan, is one of the largest mountain lakes in the world, and is famous for its magnificent scenery and unique scientific interest. It has length of 113 miles (182 kilometres), a width of up to 38 miles, and a surface area of 2,445 square miles (6,332 square kilometres). It reaches 2,303 feet in depth and has a volume of 416 cubic miles. The lake's name, which derives from a word for "hot lake", alludes to the fact that it does not freeze over during the winter, even though the lake is situated at an altitude of 5,278 feet. The first scientific investigations of Issyk-Kul took place in 1856 and were published by Russian geographer, P. P. Semyonov Tyan-Shansky, who studied the lake's bed and its connection with the Chu River. The evidence suggests that Issyk-Kul has existed at least since the Neocene (beginning 7,000,000 years ago) and that it has periodically drained. The climate is warm, dry, and temperate. Air temparatures in July on the shore average 61� or 63� F (16� or 17� C), while in January , on the western edge of the basin, the temperatures average 28� or 27� F (-2� or -3� C). More than 50 rivers can be counted in the basin. The Issyk-Kul shores open out gently, with coves on the eastern and southeastern sides. Total length of the shoreline is about 370 miles. Sandy, silt-phytogene solis predominate. Lake terraces stretch alnong the shores, indicating a higher water level in the past, and the presence of underwater ruins of buildings at depths of up to 23 feet testifies to the past that in the Middle Ages the level of the lake was lower that it now is. In the 20th century the lake has dropped more than three meters. Seasonal fluctuations of the level, caused by summer floods in the rivers of the Issyk-Kul Basin, range from 12 to 20 inches. Surface curents, which flow counterclockwise, have been recorded. The water temperature in July on the surface is 68� to 73� F (20� to 23� C), and in January it is 36� to 37� F (2� to 3� C). Ice forms only in the shallow coves. The water of the Issyk-Kul is sky blue in colour, very clear (visibility up to 65 feet), and salty (5.8 parts per thousand). Unsuitable for drinking and irrigation because of its high mineral content, it is used at times without freshening for watering cattle. Rocky deserts with sparse, saline, semibushi vegetation lie the western part of the basin. Toward the east are steppes and meadows and a type of elm that grows in the chestnut soils and black earth. Higher up in mountains, subalpine and alpine meadows occur. Forests of fir are located on the northern slopes of the Terskey Alatau Range. More than 20 kinds of fish live in Lake Issyk-Kul. The basic commercial fish are the naked soman, the chebak, the little chebak, the common carp and the marinka. The western and eastern shores of the lake serve as a wintering place for waterfowl, which gather anually in flocks of from 20 to 50,000. Pochards, mallards, bald coots, and teals are the main varieties. By the early 1970's, some 300,000 people were residing in the Issyk-Kul Basin. Kyrgyz and Russians predominate; but there are also many Ukrainians, Tatars, Uzbeks, and Dungans. There are two large cities-Karakol and Balukchu-and hundreds of villages. The majority of the population is concentrated in eastern Priissukkul. Regular boat trips are made across the lake carrying freight and passengers, and the area is joined with other regions by highways, railways, and air transportation. The shores of the Lake Issyk-Kul are noted for their health resorts, and sanatoriums and holiday houses abound. The northern shore is the main health resort area with center in town of Cholpon-Ata, but the entire lake region in mid-1970's was beginning to develop as a vacationland for visitors mainly from Central Asia and Russia.