Lake Titicaca is the highest commercially navigable lakes in the world  

Lake Titicaca is a lake Situated on the border of Bolivia and Peru. It sits 3,812 above sea level making it one of the highest commercially navigable lakes in the world.Lake Titicaca in Peru is over 170 kilometers long and lies almost 4000 meters above sea level. It is composed of two nearly separate sub-basins that are connected by the Strait of
Tiquina which is 800m across at the narrowest point.Lake Titicaca is a beautiful and much-venerated sacred lake that lies on the border between Peru and Bolivia.Recently, a large temple was discovered submerged in the lake, adding to its mystery and fascination. A natural spring here runs under the island and appears again in a sacred stone fountain in Yumani.The floating Islands of the Uros people of Lake Titicaca are formed from compacted beds of totora reeds. Walking on these spongy, unstable islands is a strange experience. The
reeds are also used to construct huts and boats. It is believed
that the Uros people originally took to the reed islands of Lake
Titicaca in an effort to isolate themselves from other groups
such as the IncasSunset on the Isla del Sol is magical and best appreciated from
the lighthouse on the highest point on the island at 13,441 feet.
The sun bathes the sacred mountains in bright colors, and
reflects its light in the deep blue of the sacred lake, before
sinking below the horizon.