As distinct from all the aforementioned geodesic lines, which may appear straight but are actually arcs of great circles projected on the spheroidal surface of the earth and, accordingly, are not truly straight but rather curving lines, authentically straight lines can be projected through the interior of the earth between almost any two points on the surface of the earth (some extreme topographical situations being the rare exceptions). If a line projected from the summit of Cayambe in Ecuador (see highest points) to the axial centre of the earth is extended to its antipode on the island of Sumatra, then the resulting diametrical line would be the longest truly straight line that could be produced anywhere on earth. As the variable circumference of the earth approaches , such a maximum diametrical or antipodal line would be on the order of long.