Maps of the Whole World Ocean

HAT the world ocean is a continuous body of water with relatively free interchange between its parts is of fundamental importance to oceanography. Because it covers more than two-thirds of the earth's surface, a map of the world ocean is essentially a world map. On ordinary world maps the interruptions forming the edges of the map are often placed in the oceans to show the continents to best advantage. If, on the other hand, oceanographic conditions as a whole are to be shown, it is desirable to have the map interrupted within the land masses and the world ocean shown as a unit. There are numerous ways in which such a world-ocean map can be constructed; discussion here will be restricted to the method applicable to a class of world maps that entail for their development a slit on the surface of the globe made between two antipodal points. In general, but not necessarily, this slit is a half great circle. If the edges of the map are not to intersect the oceans, some such line must be found which approximates a half great circle and which lies nowhere within the oceans.