The drill, entitled "Breeze", includes 20 ships, four aircraft, two helicopters, one submarine and about 17,000 troops.
The United Kingdom's Royal Navy's air defense destroyer, HMS Duncan; the Turkish frigate, Yildirim; and the Bulgarian frigate, Drazki are just three of the vessels taking part in the exercise.
The primary aim of the 10-day drill is to improve interoperability and interaction during a maritime crisis response operation.
The Bulgarian Navy started holding the Breeze drill in 1993.