Final answer:
Lake Titicaca, on the border of Peru and Bolivia, is the largest lake in South America by volume and the highest-elevation navigable lake in the world. It is second in overall size after Lake Maracaibo, which is not a true lake since it is open to the Caribbean Sea.
Step-by-step explanation:
The largest lake in South America by volume and the second largest overall after Lake Maracaibo is Lake Titicaca. Lake Titicaca is located in the Andean region of the Altiplano on the border between Peru and Bolivia, and it is considered the continent’s largest freshwater lake. While Lake Maracaibo is the largest lake by surface area, it is not a true lake as it is open to the Caribbean Sea, making Lake Titicaca the largest in terms of enclosed water volume.
It is also noteworthy to mention that Lake Titicaca is the highest-elevation navigable lake in the world, adding to its unique characteristics. Meanwhile, Lake Maracaibo, despite its larger size, has a direct connection with the sea and is therefore often classified as a large brackish bay or estuary.