Lake Titicaca is the world's highest lake navigable to large vessels. The meaning of the name Titicaca is uncertain, but it has been translated as Rock of the Puma or Crag of Lead. It lies at 12,500 feet (3,810 m) above sea level in the Andes Mountains of South America.  The sun shines brightly through the thin air at this altitude and the lake appears to be a deep blue.  The lake straddles the border between Peru and Bolivia.  Peru is to the west of the lake and Bolivia to the east. Lake Titicaca is the second largest lake of South America (after Maracaibo). The lake covers 3,200 square miles (8,300 square km).  The lake extends in a northwest-to-southeast direction for a distance of 120 miles (190 km).  It is 50 miles (80 km) across at its widest point.  It averages between 460 and 600 feet (140 and 180 m) in depth.  However, there is a point where the bottom tilts sharply and the lake reaches its greatest recorded depth of 920 feet (280 m). A narrow strait, Tiquina, separates the lake into two bodies of water.  The smaller body of water, in the southeast, is called Lake Huinaymarca in Bolivia and Lake Pequeño in Peru.  The larger body of water, located northwest, is called Lake Chucuito in Bolivia and Lake Grande in Peru. More than 25 rivers empty their waters into Titicaca.  The largest river to drain into Lake Titicaca is the Ramis River, which drains about two-fifths of the entire Titicaca Basin. Because the lake occupies the low point of the Altiplano, much of the water of the high plateau eventually trickles into the lake. Lake Titicaca is surrounded by mountains and because of this, very little water drains out of the lake through rivers. One small river to the south of the lake, the Desaguadero, is the only river to drain the lake. This single outlet empties only 5 percent of the lake's excess water. The rest of the water is lost by evaporation under the fierce sun and strong winds of the dry Altiplano. Forty-one islands rise from Titicaca's waters. Some of these islands are densely populated.  The largest island on Lake Titicaca is called Titicaca Island. Lake Titicaca also contains a group of floating Island that the Uros people of Lake Titicaca use to travel and to live on (Pictures and information about the Uros people and the islands they live on http://www.wideview.it/travel/Peru_Bolivia_2003/en_22.htm ) The floating islands are created from compacted beds of totora reeds. (pictures and information relative to totora reed and totora reed boats) http://reedboat.org The shore and the islands in Lake Titicaca contain ruins.  These ruins attest to the previous existence of one of the oldest civilizations known in the Americas, antedating the Christian era. The chief site of these ruins is at Tiahuanaco, Bolivia, at the southern end of the lake.