A Russian cargo ship believed to be carrying sensitive nuclear reactor components sank after a series of unexplained explosions off the coast of Spain, according to a CNN investigation.
The Ursa Major went down on December 23, 2024, in one of the most unusual maritime incidents in recent years. Its sinking has remained largely unexplained.
The ‘manhole cover’ confession
The ship’s manifest claimed it was carrying 129 empty containers and two large “manhole covers” to Vladivostok. The Spanish investigation found this story fell apart during interrogations in Cartagena.
Under pressure from Spanish authorities, the ship’s captain, Igor Anisimov, reportedly confessed that the “covers” were actually components for two nuclear reactors similar to those used in submarines. While he couldn’t confirm if they were fuelled, he admitted his true destination was likely the North Korean port of Rason.
CNN reports that the ship’s unusual route, from one Russian port to another via the Mediterranean, raised questions, especially given Russia’s extensive rail network that could have handled such cargo.
Scenes at sea
The ship was tracked moving along the European coast under escort from Russian military vessels.
Portuguese and Spanish authorities monitored its passage. On December 22, Spanish authorities noticed the ship slowing unexpectedly in their waters. The crew initially reported no problems.
Within 24 hours, the situation changed.
At 11:53 am UTC (5:25 pm IST) on December 23, the Ursa Major issued a distress signal reporting three explosions on its starboard side, near the engine room. Two members of the crew were killed, and the vessel began listing heavily.
Fourteen surviving members abandoned ship and were rescued by Spanish maritime services.
According to CNN, tensions escalated when a Russian escort ship, the Ivan Gren, ordered nearby vessels to stay away from the damaged ship. Spanish authorities, though, continued rescue efforts and dispatched a helicopter to search the vessel.
A second wave of explosions
Although the ship initially appeared stable, the situation worsened suddenly. Shortly after the arrival of the Russian escort ship, four other explosions were detected, with seismic readings matching underwater blast patterns. Soon after, the Ursa Major sank completely.
Spanish investigators have not publicly confirmed the cause, but CNN sources suggest the possibility of a targeted underwater strike.
Ship was carrying nuclear reactors
The Spanish government later said that under questioning, the captain “finally confessed that they were the components of two nuclear reactors similar to those used by submarines.” They added that he could not confirm whether nuclear fuel was present.
The captain reportedly believed the cargo was intended for delivery to North Korea.
Possible military intervention at sea
The investigation suggests the ship may have been disabled by a small but precise underwater strike, possibly a torpedo or limpet mine.
One theory cited describes a 50cm hull breach consistent with advanced underwater weapons. Other experts told CNN a planted explosive device could also explain the damage.
Neither Russia, Spain, nor the US has officially confirmed any military involvement.
The Ursa Major now lies at a depth of around 2,500 meters in the Mediterranean Sea. Spanish authorities say recovering its black box is currently not feasible.
Why North Korea?
The timing is critical. The Ursa Major set sail only two months after North Korea sent 10,000 troops to assist Russia’s invasion of Ukraine. The CNN report suggests the reactors were the payment for Kim Jong Un’s military support.
