Russian Cargo Ship Ursa Major Sank After Multiple Explosions Off Spain

The Russian cargo ship Ursa Major sank in the Mediterranean Sea on Dec. 23, 2024, after experiencing multiple explosions, according to a CNN report. The vessel went down about 60 miles off the coast of Spain. The ship, also known as the Sparta 3, had departed Russia on Dec.

11, 2024. Its public manifest listed only empty shipping containers, two large cranes and two large manhole covers. The vessel held a license to carry atomic materials. The Russian captain told Spanish investigators the Ursa Major was hauling components for two nuclear reactors similar to those used in submarines.

The captain said he was unsure whether the reactors contained atomic fuel and believed the cargo would be diverted to the North Korean port of Rason. The voyage occurred two months after North Korea committed to sending thousands of soldiers to assist Russian forces in the Kursk region.

Europe had been tracking the Ursa Major, with the Portuguese navy deploying aircraft to monitor the ship and its military escort vessels. By the morning of Dec. 22, the Portuguese navy ended its surveillance. The ship then slowed off the Spanish coastline.

Spanish rescuers radioed the vessel, which responded that all was fine. About 24 hours later the Ursa Major issued an urgent call for help after three explosions, likely near its engine room. The blasts killed two crew members. A Spanish rescue operation was launched.

One of the Russian military escort ships, the Ivan Gren, arrived shortly afterward. It ordered nearby vessels to stay at least two nautical miles away and demanded that Spain return the rescued crew immediately. Video from the rescue showed Spanish crews were unable to enter the ship’s sealed engine room.

The ship initially appeared stable. It sank after the Ivan Gren fired a series of flares over the scene, followed by four explosions similar to underwater mines. The wreckage lies at a depth of 8,202 feet.

Four days after the sinking, the ship’s owner, Oboronlogistics, stated that the vessel was struck in a targeted terrorist attack that left a 20-inch by 20-inch hole in its hull. A Russian research ship, the Yantar, arrived over the wreckage a week later, after which four more explosions were detected around the seabed.

Spanish authorities informed lawmakers that investigating the wreckage would be too risky without significant technical resources. The U.S. military deployed its WC-135R aircraft, known for detecting nuclear signatures, over the area on Aug. 28, 2025, and again on Feb.

6, 2026. Multiple governments have remained silent on the precise cargo and cause of the sinking.