According to the ship’s owners, an explosion caused an Estonian cargo ship to sink off the Ukrainian Black Sea town of Odesa.
The Helt’s six crew members were able to abandon ship and were later rescued, according to Ukrainian officials.
After departing port many days ago, the vessel was anchored off the coast.
According to Ukrainian media, Russian forces have been using the Helt as a shield to hide from Ukrainian weaponry as they advance.
Vista Shipping Agency, located in Estonia, owns the Panama-flagged ship. Estonia, a Nato member with a Russian border, is a Baltic state.
As it continues its push across southern Ukraine, Russia is sending amphibious landing vessels to conquer Odesa, a city of a million people and a key seaport, according to Ukraine’s military.
Russia sees the invasion as a “special military operation” to demilitarise the country.