The correct answer is - world's highest navigable lake.
Titicaca is one of the largest lakes in South America. It is high in the Andes Mountains, and has a surface elevation of 3,812 meters above sea level. The lake is located on the border between the countries of Peru and Bolivia. This lake is the highest navigable body of water on the whole planet, and is widely used by the locals for multiple purposes.
This lake is known as the lake where the Inca civilizations started off, and all around it there's numerous archaeological sites of the Incas. One of its trademarks is the very calm and seemingly still waters, as well as being very brightly reflective.