The Reykjanes Ridge is a part of the Mid-Atlantic Ridge, which stretches all the way south through the Atlantic Ocean. The Reykjanes peninsula is a continuation of the Reykjanes Ridge, but while the peninsula is above sea level, the Ridge is below the water.
The Mid-Atlantic Ridge can reach depths of 2.5 kilometres. But closer to Iceland, the Reykjanes Ridge is only about 300 metres (980 feet) below sea level.