That would be the Lena. It is the 10th longest river in the world and has the 9th largest watershed. It flows through Siberia into the Laptev Sea, which is part of the Arctic Ocean.
The Mackenzie River
it is the Columbia river.
Columbia
Congo River
The Mackenzie River in the Northwest Territories flowing from Great Slave Lake to the Arctic Ocean is a major Canadian river. Another major Canadian river is the St.Lawrence River that flows from the Great Lakes to the Atlantic Ocean.
Yenisei is the greatest river system flowing to the Arctic Ocean and is 3,445 miles long.
arctic ocean
The Saint John's River is the largest river in Florida. Beginning in the marsh of Southern Brevard County and flowing North to the Atlantic Ocean at Jacksonville.
This is a Siberian River flowing into the Arctic Ocean
The arctic ocean
Laptev Sea of the Arctic Ocean.
It empties through the Great Bear River into the Mackenzie River and that river empties into the Arctic Ocean.
There is no such thing as a "river ocean".