Known across the high plateaus of Eastern Anatolia for the ring of dormant volcanoes that surrounds it, Lake Van is not only Turkey's largest body of water but also represents a rare lake type in global terms, distinguished by its geological origin, water chemistry, and the life it supports. Its surface may resemble that of a freshwater lake, but its water is far too salty and soapy to drink — a strange chemistry that has directly shaped both the lake's ecology and the human life around it.
Geographic setting and key measurements
The lake lies within the borders of Van and Bitlis provinces, in the western part of the tectonic depression stretching between the Eastern Taurus and the Aladağlar mountains. Extinct volcanoes such as Süphan and Nemrut rise along its western and northwestern shores — this volcanic belt is also the lead actor in the story of how the lake formed.
Its surface area is roughly 3,713 square kilometers, making it Turkey's largest lake. Because its water level fluctuates from year to year depending on climate conditions, its elevation varies too, averaging around 1,646 meters above sea level. Its depth profile is equally striking: the average depth is around 170 meters, while the deepest point exceeds 450 meters. These figures make Lake Van one of the largest closed-basin lakes by volume not just in Turkey but worldwide, holding a total water volume of more than 600 cubic kilometers.
Four islands lie in the eastern part of the lake: Akdamar, Çarpanak, Adır, and Kuş (Bird) Island. Of these, Akdamar — home to a medieval church — is one of the region's most visited cultural sites. The shoreline is extremely irregular, with numerous bays and peninsulas that make the lake look less like a single basin and more like a chain of interconnected sub-basins.
How did it form? A valley sealed by a lava flow
Lake Van is not, in the classic sense, a volcanic crater lake — it is a volcanic dam lake. The outlet of an already-existing tectonic depression in the region was blocked by lava flows erupting from Mount Nemrut; once the natural drainage between the Van and Muş depressions was cut off, water accumulating in the basin formed today's lake. This lava flow is believed to have stretched for dozens of kilometers, and the event is thought to have occurred roughly two hundred thousand years ago, during the middle stages of the Ice Age.
But the lake's history does not end with this single event. Sedimentary records at the bottom of the basin show that water had been accumulating in the lake basin for far longer. Lake Van should therefore be read not as a body of water that formed "all at once," but as a long-lived basin that has repeatedly expanded and contracted, changed its chemistry, and even carried freshwater characteristics at times.
PALEOVAN: a 600,000-year archive hidden in the lakebed
The most comprehensive information about the lake's geological past comes from the PALEOVAN project, carried out in 2010 with support from the International Continental Scientific Drilling Program (ICDP). Following detailed seismic surveys, drilling was carried out at two separate points at water depths of up to 360 meters; sediment cores were recovered to a depth of roughly 140 meters in the Northern Basin and about 220 meters at the Ahlat Ridge.
These cores provide an uninterrupted continental climate record spanning the last 600,000 years. The sediments were dated using a range of mutually reinforcing methods, including comparison of climate layers, annual layer (varve) counting, analysis of volcanic ash layers, argon–argon and radiocarbon dating, magnetostratigraphy, and cosmogenic isotopes. The detection of hundreds of separate volcanic ash (tephra) layers throughout the core provides concrete evidence of just how intense volcanic activity in the basin has been over the past several hundred thousand years. The lowest sediments are especially significant, as they indicate that the lake's earliest phase began under freshwater conditions.
Because this record makes it possible to trace not only Lake Van's own history but also the droughts, water-level collapses, and earthquake–volcanic activity experienced across all of Eastern Anatolia and the Near East through glacial–interglacial cycles, it serves as a reference point among mid-latitude lakes.
The chemistry of the water: why doesn't it freeze, why is it salty?
Lake Van is a closed basin — it has no outflow. Dissolved minerals carried in by streams entering the basin accumulate in the lake, while water is lost only through evaporation. Over hundreds of thousands of years, this cycle has caused the concentration of dissolved carbonates and salts to rise. As a result, the water's salinity has reached around 19 parts per thousand, and its pH has reached a range of 9.7–9.9 — distinctly alkaline.
This chemical makeup explains one of the lake's most striking features: despite its high elevation and harsh continental climate, with long, freezing winters, the lake's surface never freezes. Because dissolved salts lower water's freezing point, small lakes in the surrounding area ice over while Lake Van remains open water. This same soda-rich composition is also the traditional reason the lake's water was used for washing clothes in place of soap.
This alkaline, soda-rich water also creates conditions favorable for the formation of microbially derived carbonate structures in the lake. These tower-like carbonate formations, rising from underwater near the shoreline, are produced by microorganism communities resembling some of the earliest forms of life on Earth, drawing the interest of both geologists and biologists alike.
A single fish in a harsh environment: the Van pearl mullet
The chemistry of Lake Van's water limits its biological diversity. While the lake hosts hundreds of plankton species, the only fish species that has adapted to these conditions is the Van pearl mullet (Alburnus tarichi). A member of the carp family, this species has adapted to high salinity and high pH conditions, becoming a value endemic to the Lake Van basin.
The pearl mullet's life cycle is directly tied to the lake's chemistry. The fish feeds and grows in the soda-rich water, but it cannot lay its eggs there. For this reason, every year between April and July, it migrates in large schools toward the streams flowing into the lake to spawn. After spawning in fresh water, the fish return to the lake. This migration, which advances in numbers dense enough to change the color of the water at stream mouths, is one of the region's most striking natural events.
This migration is also the moment the species is most vulnerable: schools crowded into narrow streambeds become easy targets for illegal fishing. For this reason, fishing bans are enforced during the spawning season, and conservation and control efforts are intensified. The pearl mullet constitutes Turkey's largest inland fish stock and directly supports the livelihoods of more than fifteen thousand people around the lake. The fact that a significant share of the fish caught from Turkey's inland waters nationwide comes from this single species reflects the economic weight of this resource.
The threats facing the species are not limited to illegal fishing. In the streams where it migrates to spawn, sand extraction, streambed interventions, water intake structures, and drought-related reductions in flow prevent the fish from reaching upstream stretches, lowering reproductive success. In some streams, catch per unit effort has reportedly declined dramatically over the decades.
A changing water level and the future
Closed-basin lakes respond quickly even to small shifts in the balance between precipitation and evaporation. Lake Van's water level has likewise risen and fallen throughout history — in periods of rising water it has submerged farmland and settlements along the shore, while in periods of falling water it has exposed broad coastal plains and underwater microbial carbonate formations. The receding shoreline observed in recent years shows that rising drought in the region and water use within the basin are issues that must be considered together. The past drought periods revealed by sediment records extracted from the lakebed also offer a concrete reference point for today's discussions on water management.