Tankers that transfer Russian oil off the southern coast of Greece sailed further out into the Mediterranean after naval exercises were announced in the area where the cargo switching normally takes place.

The activities, which began on May 1, will continue through May 9, the Hellenic Navy Hydrographic Service said in a notice on its website. The activity takes place almost exactly a month after Denmark briefly closed a shipping lane through which Russian oil flows on tankers while similar activity took place.

When sanctions were placed on Russian oil sales following the war in Ukraine, the Laconian Gulf became a key spot for switching cargoes between vessels. It enabled some ships to shuttle to and from Russian ports, and others to do the long-distance voyages to buyers in Asia. However, it also sparked environmental concerns about the risk of an oil spill in a picturesque European bay. 

Since the start of this month, vessels have left the gulf and are instead clustered just to its south, according to TankerTrackers.com Inc. 

Away from the gulf, one tanker also flipped a cargo of crude onto another vessel in the Red Sea in April. The Panta Rei 1 transferred its cargo onto the Odysseus, which then transported its consignment to India. That’s the first ever switch observed in that location in ship tracking data compiled by Bloomberg.

The Laconian Gulf has hills all around it, offering some protection from the wind, and calm waters. That has made it a useful spot for transferring cargoes and helps to reduce environmental risks. 

On a trip to the Port of Piraeus this week, Greek Shipping Minister Christos Sylianides said the safety of the country’s shipping is above all other things.