The Great Northern Expedition or Second Kamchatka expedition is one of the largest organized exploration enterprises in history, resulting in mapping of the most of the Arctic coast of Siberia and some parts of the North America coastline, greatly reducing the "white areas" on the maps.

The endeavor had initially been conceived by Russian Emperor Peter I the Great and is implemented in practice by Russian Empresses Anna and Elizabeth.

The main organizer and leader of the expedition is Vitus Bering, who earlier had been commissioned by Peter I to lead the first Kamchatka expedition.

The Second Kamchatka expedition lasts roughly from 1733–1743 and later becomes called the Great Northern due to the immense scale of its achievements.The goal of the expedition is to find and map the eastern reaches of Siberia, and, if possible, to continue onto the western shores of North America to map them as well.

Emperor Peter I had had a vision for the 18th-century Russian Navy to map the entire Northern Sea Route.

This far-reaching endeavor is sponsored by the Admiralty College in St. Petersburg.With over 3,000 people directly and indirectly involved, the total cost of the undertaking, completely financed by the Russian state, reaches an estimated sum of 1.5 million rubles, an enormous amount for the time.

This corresponds to one sixth of the income of the Russian state for year 1724.

The important achievements of the expedition include he European discovery of Alaska, the Aleutian Islands, the Commander Islands, Bering Island, as well as a detailed cartographic assessment of the northern and northeastern coast of Russia and the Kuril Islands.

The expedition also definitively refutes the legend of a land mass in the north Pacific.

It also includes ethnographic, historic, and scientific research into Siberia and Kamchatka.

When the expedition fails to round the northeast tip of Asia, the dream of finding an economically viable Northeast passage, alive since the 16th century, comes to a definitive end.