Elbe
The Meuse River flows into the North Sea. It begins with the letter M.
A North Sea Feeder beginning with the letter Y could be the York River estuary, which connects to the North Sea via the Humber Estuary in England.
A river that runs into the Yellow Sea, or feeds into it. The Han river is one such river.
That would be the river Ems in the Netherlands.
Yser
No river runs from the North Sea to Switzerland. That is uphill, and no river runs uphill!The river Rhine runs in the opposite direction, from Switzerland to the North Sea.
The River Thames flows into the North Sea between the Counties of Kent and Essex.
North of the Nile is the Mediterranean Sea
The Weser river.
The Rhine River flows into the North Sea near Rotterdam in the Netherlands.
Just north of Japan is the Sea of Okhotsk.
The North Sea