The tug ATOLL, which was escorting a pontoon with the drilling rig from the port of Kavkaz to Primorsko-Akhtarsk sank five miles offshore in the Sea of Azov. The six crew members evacuated themselves from the stricken vessel to the pontoon, said the Russian Emergencies Ministry.
The incident cause is unclear. The crew of the tug was evacuated to the port of Temryuk by the tug Vasiliy Klimov (homeport Port Kavkaz).