The northern extension of the Mid-Ocean Ridge under the Arctic
Ocean, separating the North American Plate from the Eurasian Plate, connected
to the Mid-Atlantic Ridge via the strait between Greenland and Svalbard. Named after Soviet Arctic explorer Yakov Yakovlevich Gakkel.
Imagine the process of tearing a piece of paper lengthwise: You begin
your tear at one edge of the paper, and it extends through the paper. At
the tip of the tear, the two halves of the paper are still connected to
each other.
Now imagine peeling an orange. You have a tear that extends
some distance around the orange, but most of the tearing force is applied
away from the tip. Near the tip, it tears much more slowly.
The Gakkel Ridge is the tip of a tear in the Earth's crust. It extends
northeast from Greenland, missing the North Pole by about 250 mi (400
km), then travelling southeast to end somewhere under the continental shelf
underlying the Laptev Sea. The ridge follows a great circle; directions like "north" and "east" begin to lose their meaning near the North Pole.
For the reasons of orange-peel physics stated above, the ridge is the
slowest active spreading center in the world: the ridge's spreading formed the Eurasia Basin, which is much narrower than the Atlantic Ocean. For the same
reason, the continental crust of Siberia is fused with the continental
crust of Alaska and the rest of North America, making it impossible to
determine part of the boundary between the North American Plate and the Eurasian
Plate.
Idle speculation on my part:
It is possible that a tear in the lower lithosphere extends from the
southeastern end of the Gakkel Ridge under Siberia to emerge in the Pacific
Ocean off the Kamchatka Peninsula, where the Aleutian Trench meets
the Kuril Trench. As this is the same point that the Emperor Seamounts
emerge, and since the Emperor Seamounts are connected to the Hawaiian
Island chain, it is possible that the same hot spot that formed the Hawaiian
Islands created the crustal weakness in Pangaea leading to its breakup,
that is, the formation of the Atlantic Ocean.