the korean demilitarized zone () is a piece of land running across the korean peninsula that serves as a buffer zone between north and south korea. the dmz cuts the korean peninsula almost in half, crossing the 38th parallel. the west end of the dmz is south of the parallel and the east end is to the north of it. it is long, and about wide and is the most highly militarized border in the world. the border between both koreas in the yellow sea and its coastline is known as the northern limit line. both sides of the northern limit line are also heavily guarded.