Lake Donuzlav (Crimean Tatar: Doñuzlav/Донъузлав, Russian: Донузлав) also referred to as Donuzlav Bay is the deepest lake of Crimea (27 m) and biggest in Chornomorske Raion (47 km²). It is a protected landscape and recreational park of the Autonomous Republic of Crimea.
In practice it is no longer a lake but rather a bay since 1961, when a sandy spit (200–400 m wide) separating it from the Black Sea was dug out with a 200-metre width channel. The lake is as salty as the sea near its mouth but bottom springs make the water much more sweet near the head.
Donuzlav is well known for a top secret naval base that was established here in 1960s as the Soviet Crimean Naval Base. The base was particularly notable for housing air-cushioned landing crafts (Zubr class). Following the dissolution of the Soviet Union, the base was passed to the Armed Forces of Ukraine and was one of the three main naval bases as the Southern Naval Base (Ukraine). After the Russian invasion of Ukraine in 2014 the base was occupied by the Russian military that reinstated its previous name.
Donuzlav is located in Chornomorske and Saky raions (districts) at the Tarkhankut peninsula as well as Yevpatoria Municipality. Donuzlav is one of several lakes located around the peninsula. It is separated from the Black Sea by a 12 km (7.5 mi) long sandbar that has a width of 0.3 km (980 ft) to 1 km (3,300 ft). Donuzlav is connected to the sea by a ship channel.