According to unofficial reports, the crew managed to evacuate, avoiding casualties.
from thefreeonline on 1st Feb 2024 from SouthFront

The Russian Black Sea fleet lost the missile corvette Ivanovets as a result of the night attack of unmanned boats near the coast of the Crimean peninsula. The Main Intelligence Directorate (GUR) of Ukraine claimed the destruction of the warship and supported the report with footage of the attack.
The operation was reportedly carried out by the special unit “Group 13” of the GUR with the support of the Ministry of Digital Transformation of Ukraine and the United24 platform.

The Russian Ministry of Defense did not comment on the incident.
Russian military sources revealed details of the attack. In total, 9 unmanned boats were reportedly launched from the Danube River in the Odessa region. The crew of the Russian Ivanovets took the battle near the Lake Donuzlav. At least four boats were reportedly destroyed by Russian fire.
The footage shows that after the first drone exploded right next to the vessel, inflicting heavy damage, the crew did not stop fighting and fought till the last to save the corvette.
In total, three drones reportedly hit the vessel. As a result of the strikes, the missiles on board of the corvette exploded and Ivanovets sunk.
According to unofficial reports, the crew managed to evacuate, avoiding casualties.

Putin inaugurates two fourth generation nuclear submarines 11 Dec, 2023
The missile corvette Ivanovets was built in 1989. It is armed with supersonic low-altitude anti-ship cruise missiles “Mosquito”. The cost of the warship is estimated at about $ 60 million.
The attack of naval drones is the latest in a series of Ukrainian drone and missile strikes over the past two days. LINK
At the beginning of the war Turkey invoked the Montreux treaty forbidding naval shops passing in and out of the Black Sea in wartime. NATO and Russia now cannot get in or out which favours Russia as NATO has a huge fleet. Turkey’s move, in this case, undoubtedly made the war less dangerous and may have prevented a third world war.
Although several Russian ships have been destroyed in the war probably more new ones have been commissioned. However Ukraine is being supplied with advanced NATO naval drones, and missiles, sabotage specialists and detailed information on Russian movements by NATO AWACS planes and satellites.
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