Lake Ohrid (Macedonian: Охридско Езеро Ohridsko Ezero ; Albanian: Liqeni i Ohrit ) is a lake which straddles the mountainous border between the southwestern part of North Macedonia and eastern Albania. It is one of Europes deepest and oldest lakes, with a unique aquatic ecosystem of worldwide importance, with more than 200 endemic species.



North Macedonias side of Lake Ohrid was declared a World Heritage Site by UNESCO in 1979, with the site being extended to also include the cultural and historic area of Ohrid in 1980. In 2010, NASA named one of Titans lakes after it. In 2014, the Ohrid-Prespa Transboundary Reserve between Albania and North Macedonia was added to UNESCOs World Network of Biosphere Reserves. Albanias side of Lake Ohrid was also designated UNESCO world heritage status in 2019. North Macedonias portion was designated as a protected Ramsar site in 2021, passing all nine criteria for proclamation.




The water at the surface of Lake Ohrid moves predominantly in a counter-clockwise direction along the shore, as a result of wind forcing and the Earth rotation, similar to the Ekman-phenomenon known from oceans. In terms of vertical water exchange, convective mixing during winter cooling is the dominant process. However, in an average winter only the top 150–200 meters of the lake are mixed, whereas the water below is stably stratified by salinity. The stability due to this salinity gradient allows complete convective mixing events only roughly once every 7 years





Measured by its surface area of 358 km², Ohrid is probably among the most biodiverse lakes on Earth. While it is special as such, by far the most spectacular quality is its impressive endemism. Similar to Lake Baikal or Lake Tanganyika, Lake Ohrid harbors endemic species covering the whole food-chain, from phytoplankton and sessile algae (20 species; e.g., Cyclotella fottii), over plant species (2 species; e.g., Chara ohridana), zooplankton (5 species; e.g., Cyclops ochridanus), cyprinid fish (8 species; e.g., Pachychilon pictum), to predatory fish (two trout species; the Ohrid trout complex Salmo letnica, and Belvica Salmo ohridanus) and finally its diverse endemic bottom fauna (176 species; e.g. Ochridagammarus solidus), with particularly large endemism among crustaceans, molluscs, sponges and planarians. There were recorded 68 species of freshwater snails from the Lake Ohrid basin. 73.5% (50 species) of the total freshwater gastropod fauna appear to be endemic to the Lake Ohrid başın. Whereas the endemic species list cited above is based on morphological and ecological characteristics, some recent applications of molecular genetic techniques underline the difference of the fauna from common European taxa, as well as the old age of the lake.

Quite remarkably, exotic species do not seem to be a major issue in Lake Ohrid, although they have been recorded in small populations for several decades or exist in nearby rivers or lakes. The reason lies very probably in the ideal adaptation of the endemic species to the specific conditions in the lake, such as low nutrient availability, good living conditions in greater depth thanks to high water transparency and oxygen content, as well as subaquatic spring inflows supplying cool and oxygen-rich water. In total, seven introduced fish species are known from the lake. 

Despite the exceptionally high level of endemism in Lake Ohrid (for example, a third of the 21 native fish species and almost 80% of its 72 mollusc species are endemic), a significant number of non-endemic species are found in Lake Ohrid. This includes species, which are mobile (e.g., via water birds) or migratory, such as the European eel.. 



The lakeshore reed beds and wetlands provide critical habitat for hundreds of thousands of wintering water birds, including rare and threatened species such as the Dalmatian pelican, ferruginous duck, swan, spotted eagle, and eastern imperial eagle. The Macedonian part of the lake has been designated an Important Bird Area (IBA) by BirdLife International because it supports populations of common coots and pygmy cormorants (Microcarbo pygmaeus). The Albanian part of the lake has been designated a separate but corresponding IBA for the same reason, with additional bird species being common goldeneyes, red-crested pochards (Netta rufina) and black-necked grebes. Wetland of International Importance status under the Ramsar Convention is underpinned in part by the biogeographically significant populations of red-crested pochard and pygmy cormorants too, but also goosander (Mergus merganser)














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