From an earlier answer of mine

Well, humans did discover the Americas via the northern Pacific, many, many, many years before Columbus. The overland and coastal explorations via Asia in the Bering region around 16-20,000 years ago. The exact dates are fuzzy, but this is long before any recorded history and the Bering route was the origin point for the peopling of the Americas. There is some evidence too of later Polynesian contact with the Americas- see /u/b1uepenguin 's answer here for more details. So there were multiple "discoveries" of the Americas that stretch back a considerable period.

As for European discovery of the Americas- the northern Pacific route was not a really viable route for an exploration of the Americas in 1492. The Grand Duchy of Moscow (aka Muscovy)- which is the name of Russia ca. 1492- had not really expanded to the Pacific. This map shows that the furthest extent of Moscow's in the late-fifteenth century was just about to the Ural mountains. The seventeenth and eighteenth centuries witnessed an increased Russian penetration of Siberia, as seen in this map. This expansion was a simultaneous missions for setting up trading missions, bringing the various Siberian peoples under political control, small-scale settlements, and for exploration. Ivan Moskvitin reached the Pacific in 1639 and the Danish emigre Vitus Jonassen Bering explored the sea between Alaska and Asia that would bear his name in the 1730s. Expeditions like Moskvitin's and Bering's were grueling and covered vast distances. The space between Moscow and the Pacific is large and very demanding terrain. Siberia is not just the stereotypical frozen tundra, but also includes vast forests and swamp land like the Vasyugan Swamp. Exploring the region was difficult and settling the area was an even greater long-term process.