Only a small section of this classic route passes through Northumberland, but what a section! The highest point of the C2C at Black Hill (609m) is on Northumberland/Cumbria Border offering a unique view into not just Northumberland but County Durham, and Scotland.
The C2C is an excellent way to travel into Northumberland by bicycle, and connects up with ALL of the other long distant routes featured.
Take a look at the following link for more information on the C2C (aka Sea to Sea) Cycle Route.