 The Kara Sea was formerly known as Oceanus Scythicus or Mare Glaciale and it appears with these names in 16th century maps.Since it is closed by ice most of the year it remained largely unexplored until the late nineteenth century.In 1556 Stephen Borough sailed in the "Searchthrift" to try to reach the Ob River, but he was stopped by ice and fog at the entrance to the Kara Sea.