New data compiled by the Danish Maritime Authority reveals that EU-sanctioned tankers linked to Russia’s so-called “shadow fleet” made 292 voyages through Danish territorial waters in 2025, underscoring the strategic importance of the Danish straits as a gateway to the Baltic Sea.
Denmark’s narrow straits, the Øresund, the Great Belt and the Skagerrak, are vital sea lanes providing access to and from the Baltic for Russian oil exports, including traffic bound for ports near St. Petersburg and Primorsk. Those waters now regularly see tankers that have been cut off from traditional Western insurance and shipping services by sanctions imposed since Russia’s full-scale invasion of Ukraine.
“In 2025, there were 292 voyages with EU sanction-designated tankers in Danish waters,” the authority said according to the AFP. The figure highlights how sanctions aimed at choking off revenue for Moscow’s war economy have been met with creative work-arounds that still allow crude and refined products to transit crucial maritime corridors.
Denmark’s position at the entrance to the Baltic Sea makes it a frontline state in enforcement efforts. The authority said: “The Danish authorities are closely monitoring ships in Danish waters” and “also cooperate closely with like-minded countries in the Baltic Sea region,” adding that “in addition, a number of concrete measures have been taken to strengthen maritime safety and the protection of the marine environment and seafarers.”
The so-called shadow fleet has grown markedly since the G7 and EU oil price cap sanctions took effect in 2022. That network of aging tankers, often operating under flags of convenience and with opaque ownership, is estimated to number hundreds of vessels. Many of the vessels have been individually designated on EU sanctions lists and nearly 600 such tankers are banned from EU ports and maritime services.
Efforts by Baltic coastal states to counter shadow fleet activity extend beyond monitoring. In January, German authorities refused entry to the tanker Tavian, a vessel with a long history of name changes and suspected sanctions evasion when it attempted to transit into the Baltic Sea. Other Baltic states have boarded or detained vessels, Estonia once detained the Aframax tanker Kiwala for inspection, and Finland’s coast guard has cited incidents of cable damage attributed to similar tankers.
Security analysts caution that these vessels pose economic, environmental, and strategic threats. Many are poorly maintained, uninsured and sail without reliable tracking, raising the risk of collisions, oil spills or infrastructure damage in densely trafficked waters. The combination of opaque ownership and minimal safety oversight has allowed them to skirt regulatory controls while moving oil to buyers in Asia, the Middle East and Africa. The Danish Maritime Authority’s data underscores the challenge of enforcing sanctions in international seas.
A similar pattern is visible farther west. In the English Channel, 9,584 voyages by tankers carrying Russian oil have been recorded since early 2022, moving an estimated 550 million barrels of crude and petroleum products valued at $325bn through the Strait of Dover, a passage that also serves as an artery for shadow fleet traffic bound for markets outside Europe.
Despite mounting concerns and the fact that vessels continue to transit, no sanctioned ship has yet been seized or denied passage through the English Channel by UK or French authorities solely on sanctions grounds, according to maritime security analysts.
While the UK has not independently seized any vessel, the Royal Navy and RAF provided surveillance and support to US forces seizing the tanker Marinera in the North Atlantic and assisted the French Navy in seizing a vessel, the Grinch, in the Mediterranean in January 2026.
However, London is considering a tougher approach. British defense officials have signaled plans to more aggressively enforce actions against shadow fleet vessels in the Channel, including legal options to board or seize stateless tankers under international law, and increased cooperation with NATO allies to curb sanctions evasion.
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