In August, Maersk - the world’s largest shipping line - braved the ice to send its first container ship through the northern route from Vladivostok through the Bering Straight to St Petersburg.

Ships sailing the route require a permit from Russian authorities.

The vessel was the Venta Maersk ice-class container ship that carries 3600TEUs.  The northern sea route has become more accessible as a result of melting sea ice caused by climate change.

The route is shorter than the alternative via the Suez Canal but is only navigable, even with retreating ice, for a few months each year.  For this reason, plus the additional costs for insurance, ice-breaker escorts and the unpredictability of the ice coverage, it is unlikely to be commercially viable for some time.