The drill, the first in Turkey since 2000, is aimed at demonstrating multinational submarine rescue cooperation and interoperability. But its hosting by Turkey is also a symbol of Ankara's importance within the alliance during a tense period.
"I would just recognise that the Turkish navy have consistently continued to be one of the greatest supporters of my command," said the head of the NATO maritime force, Vice Admiral Clive Johnstone.
A NATO official, who asked not to be named, added: "Turkey is essential for the security of Europe. It has NATO's second largest army and makes an important contribution to the alliance including our missions in Afghanistan, Kosovo and the Aegean Sea."
The manoeuvres got underway earlier this month and the press were permitted to witness the drill on Wednesday, with the operation due to wrap up on Friday.
Mainly Muslim Turkey is one of NATO's key members, having joined in 1952.
However its relations with several key alliance members, in particular Germany, have been damaged over the merciless crackdown after last year's failed coup.
Ankara in turn accuses EU states of failing to round up Kurdish militant and coup plot suspects.
Ties with the United States meanwhile have been hurt by Washington's support of a Syrian Kurdish militia Ankara regards as a terror group.
The exercises come just a week after Turkey ruffled feathers within NATO by announcing it had signed a deal with Russia to purchase Moscow's sophisticated S-400 air defence systems.
NATO officials warned that interoperability of equipment was crucial between alliance members but President Recep Tayyip Erdogan has shrugged off the warnings.
Analysts have however warned that despite the signing, thorny issues still need to be resolved before delivery including Turkey's demand for technology transfer and Russia's order backlog for the hardware.
Financial details have not been disclosed but according to Russian press reports the deal is worth $2 billion with Turkey seeking a credit from Russia to assist the payment.
