"The Sea on the East" by George Potter

In my book Nephi in the Promised Land, I propose that the Nephites' "sea on the east" is the 118-mile-long freshwater Lake Titicaca. The age and location of the ruins surrounding the lake are consistent with the Book of Mormon account. Throughout their oral history and up to the present day, the Aymaran Indians on the south side of the lake hate the taller Quechua Indians on its north side. This hatred has led to countless wars between the two peoples. The Book of Mormon describes the Nephites and Lamanites as having been separated by the sea on the east.
 
Lake T
Lake Titicaca
Thor Heyerdahl was initially drawn to construct his raft the Kon-Tiki and sail it from Peru to Polynesia to test his theory that white-skinned people from Peru colonized parts of the Pacific. In fact, the name of his raft, the Kon-Tiki, came from the Peruvian legend that inspired his theory. He wrote:

As I pursued my search, I found in Peru surprising traces in culture, mythology, and language which impelled me to go on digging ever deeper and with the greater concentration in my attempt to identify the place of origin of the Polynesian tribal god Tiki.

And I found what I hoped for. I was sitting reading the Inca legends of the sun-king Virakocha, who was the supreme head of the mythical white people in Peru. I read:

....Virakocha is an Inca (Ketchua [Quechua]) name and consequently of fairly recent date. The original name of the sun-god Virakocha, which seems to have been more used in Peru in old times, was Kon-Tiki or Illa-Tiki, which means Sun-Tiki or Fire-Tiki. Kon-Tiki was high priest and sun-king of the Incas' legendary 'white men' who had left the enormous ruins on the shores of Lake Titicaca. The legend runs that the mysterious white men with beards were attacked by a chief name Cari who came from the Coquimbo Valley. In a battle on an island in Lake Titicaca the fair race was massacred.... 1.

There are many similar legends of a tall fair-skinned people having lived around the northern shores of Lake Titicaca and on the lake's Isle of the Sun.

But how can a fresh-water lake be a sea? In the Quechua language, Lake Titicaca is called "Cocha Titicaca." Cocha means sea, not lake. For example, the Incas called the Pacific Ocean a "cocha." The same is true in the Hebrew language where a fresh water lake is also a sea  (Sea of Galilee, see Matthew 4).

1. Thor Heyerdahl, Kon-Tiki, translated by F.H. Lyon, (New York: Washington Square Books, 1984.