 Both the Ob and Yenisey mouths feed into very long inlets, several hundred kilometres in length, which are shallow, ice bound and prone to high winds and thus treacherous for navigation.After the completion of the railway, river traffic reduced only to local service as the Arctic route and long river proved much too indirect a route.The first recreation team to navigate the Yenisey's entire length, including its violent upper tributary in Mongolia, was an Australian-Canadian effort completed in September 2001.