The set of stamps was issued by Argentina in honor of the 125th anniversary of the Argentine Hydrographic Service. The map which provides the background for the four stamps is a map of the Rio de la Plata drawn by Don Andrés Oyarvide probably around 1777 when he was in the region as a member of the Demarcation Party which fixed the boundaries between the Spanish and Portuguese territories. It was corrected in 1823 by D. Benito Aizpurua.
     The map shows the region at the mouth of the River Plate. Today Buenos Aires is located on the west bank of the river in the upper left hand corner where the river turns north. Montevideo, Uruguay is located on the east bank of the river on the point of land a little to the right of the bottom of the sextant.
     Although the map does not show the location, the lighthouse in the lower left stamps the located at Cape Virgins, the southern-most tip of the continental western hemisphere. It was established in 1904, and is in service today.