Two Russian research vessels that offered expeditions in the Polar Regions won’t sail again as cruise ships.

The Akademik Ioffe and Akademik Sergey Vavilov had previously been chartered to now-defunct One Ocean Expeditions, and will no longer be available to charter for cruise operations.

Since being recalled to Russia last May, the vessels have sat idle and are now being modernized for a return to their careers as research vessels.

“The ships are not available for any customers since they are undergoing modernization and will be thereafter used for research purposes,” said a statement from the ship’s owners, the P.P. Shirshov Institute of Oceanology Russian Academy of Sciences.