A major earthquake occurred in 1306, the Sabayil Castle, built on an island in the Bay of Baku, was submerged and remained underwater for several centuries.

[3] Mario Sanuto, an Italian geographer of the 14th century sadly noted that: "Water level of the Caspian Sea rises each year and most cities have flooded.

", and according to words of Abd ar-Rashid al-Bakuvi, the geographer, in 1403 the Caspian Sea flooded the part of Baku and water stood near a mosque.

During the next 600 years, the level of the sea was hesitatingly stood high till the beginning of the 20th century when it began to sink.

Wastes from industrial, dwelling and domestic objects located on the seashore and also exploitation of vessels, oil and gas deposits are the main factors that worsen the ecological condition.

Foreign companies plan to open a recreational center in Boyuk Zira and Pirallahi islands of Baku bay.

In Azerbaijani newspapers is reported that a Turkish company which is preparing an appropriate project will hold the construction of the recreational center in Nargin Island.