Суэз каналының Ұлы Ащы көлі

Saltwater lake that is part of the Suez Canal in Egypt

The Great Bitter Lake (البحيرة المرة الكبرى; transliterated: al Buḥayrah al Murra al Kubrā) is a large saltwater lake in Egypt which is part of the Suez Canal. Before the canal was built in 1869, the Great Bitter Lake was a dry salt valley or basin. References are made to the Great Bitter Lake in the ancient Pyramid Texts. The canal connects the Great Bitter Lake to the Mediterranean Sea and the Red Sea. The canal also connects it to the Small Bitter Lake (البحيرة المرة الصغرى; transliterated: al Buhayrah al Murra as Sughra). Ships traveling through the Suez Canal use the Great Bitter Lake as a "passing lane", where they can pass other ships or turn around.

The Modern English and Arabic names are translations of the Greek name (Πικραὶ Λίμναι). It was also known in Latin as "dead lake" (Lacus mori). The ancient Egyptian name for the Bitter Lakes region was km wr, lit. "great black one".

The salinity of the lake varies along its depth and is highest at the bottom where the water is in contact with the preexisting salt deposit, which has been consistently diminishing due to dissolution –thereby steadily increasing the depth of the lake– since the canal started operation in 1869. Salinity is subject to seasonal variation as a result of yearly evaporation cycles. In the early 20th century, the minimum and maximum values were measured as 45‰ and 54‰, respectively, with an average salinity of 49‰ (i. e. 49 g of salt per kg of lake water). Even when the canal is open, in certain places the Great Bitter Lake can have a salinity level "more than twice" the level of the sea. While this makes plant life difficult to exist there, many species (of crabs, for example) migrate from the Red Sea through the area. As the canal has no locks, seawater flows freely into the lake from the Mediterranean and the Red Sea. In general, north of the lakes, the current reverses seasonally, being north going in winter and south going in summer. South of the lakes, the current is tidal, reversing with the tides in the Red Sea. Fish and crabs can migrate, generally in a northerly direction, through the canal and lakes in what is known as a Lessepsian migration, as some Red Sea species have come to colonize the eastern Mediterranean. The first recorded molluscan anti Lessepsian migrant was Cerastoderma glaucum by Fisher (1870). The hypersaline state of the water in the lake was found to make faunal and floral growth impossible there. Nevertheless, some seaweed was found on the eastern side of the lake, giving a slight hope of prolific biotope. (table 1) and 19 bivalve species (table 2) are documented in the lake.

The Great Bitter Lake’s bottom soil is mainly composed of mud and sand (mostly carbonate), Several factors determine the availability of heavy metals at the bottom of the lake. In the recent years, a major part of heavy metal pollution has originated from overpopulation, industrialization, sewage, dumpsites, crude oil spills, agricultural chemicals, and more. President Roosevelt's interpreter was U. S. Marine Corps Colonel Bill Eddy, who recorded the men's conversation in his book FDR Meets Ibn Saud. The meeting is the subject of a BBC documentary by Adam Curtis, entitled Bitter Lake (2015).

During the Six Day War in 1967, the canal was closed. Egypt kept it closed until 1975, trapping 15 ships in the lake. These ships became known as the "Yellow Fleet", because of the desert sands that soon covered their decks. The crews of the ships eventually organized, shared resources, and later set up their own post office and stamp. Two German flagged ships eventually sailed out of the canal on their own power. Stranded cargo included various perishables (such as eggs and fruit), T shirts, and a load of toys destined for Woolworth's.