What do Inca/other stories, legends, and histories tell is across the sea? Is there a tradition of speculation on this front?
I am vaguely aware of the myth of Viracocha coming from the sea, or across the sea, but I don't know much more than that. Do we have any record or oral tradition that tells of what the literate/intellectual elite of pre-Columbian South American Pacific coast believed would be found, and whether that was the same as what the common people believed?
Did they think of the sea as endless or finite, did they tell stories of peoples or other beings across the water, that sort of thing. Basically, roughly what was the cultural, religious, or mythical relationship with the sea in Incan or other nearby/predecessor cultures?
The Inca empire or Tawantinsuyu—literally meaning "four regions/quarters together" in their language—have definitely had associations with the sea and had thoughts about it. They were settled in the Andes region, only having the Pacific Ocean as their only limit to westward expansion.
Just as you recall the lore and legends involving Viracocha, the Pacific Ocean was the area he was thought to have departed from the whole civilization forever. According to his creation lore, he left by walking over the Pacific Ocean once helping the Incan civilization rise and establish their capital, Cuzco. Hence, why Viracocha's name literally means "foam (of the) sea." He was thought to have originated from the most sacred body of water to the Inca, Lake Titicaca. Another deity associated with seas and bodies of water was Mama Qucha, having familial relations to Viracocha, was revered by the Inca when trading along the coasts, fishing, and protection from disasters like floods and tsunamis.
Because the Inca heavily relied upon oral traditions for communication and stories—other than the situational quipu knots—the information about the Inca was scarce unfortunately. Just as any other large pre-Columbian civilization, there were barely any written history or evidence intact due to them being lost, no ethnographers or Spanish chroniclers either destroying or not being interested in their history. We also do not have enough people researching about the Inca and other Andes civilizations due to lack of interest or evidence than others that are convenient, like the Mayans.
However, there are many theories and genetic traces of Polynesian-South American contact between each other. This includes the supposed Pacific Expedition launched by the noble Topa Inca Yupanqui. Many claim he may have found the Galapagos Islands, Easter Island and other east Polynesian islands like the Marquesses Islands. In 1572, Spanish explorer Pedro Sarmiento de Gamboa was an author of a book about the Inca and the voyage, titled "Historia de Los Incas". Here are some excerpts translated mentioning the voyage of Tupac Inca Yupanqui:
Tupac Inca navigated and sailed on until he discovered the islands of Avachumbi and Ninachumbi, and returned, bringing back with him black people, gold, a chair of brass, and a skin and jaw bone of a horse. These trophies were preserved in the fortress of Cuzco until the Spaniards came…
An Inca now living had charge of this skin and jaw bone of a horse. He gave this account, and the rest who were present corroborated it. His name is Urco Huaranca. I am particular about this because to those who know anything of the Indies it will appear a strange thing and difficult to believe. The duration of this expedition undertaken by Tupac Inca was nine months, others say a year, and, as he was so long absent, every one believed he was dead…”
And another about what Yupanqui supposedly brought to Cuzco (14th footnote, pg. 30):
^(14) Sarmiento de Gamboa conocía muy bien las leyendas indígenas sobre las islas al oeste de la costa del imperio incaico, las cuales el mismo inca Túpac Inca Yupanqui habría logrado visitar y traer consigo en su mítico viaje de retorno indígenas de piel negra, una gran cantidad de riquezas y pieles de animales semejantes a los caballos.
[Translation] Sarmiento de Gamboa knew very well the indigenous legends about the islands west of the Inca empire, which the Inca Tupac Inca Yupanqui himself would have managed to visit and bring with him in his mythical journey of return indigenous of black skin, a lot of riches and horse-like animal skins.
It is a mystery what he meant by creatures resembling horses and dark-skinned people.
Similarly, some researchers think that's how sweet potatoes got to New Zealand, originating in South and Central America. Also, the name for sweet potato in many Polynesian languages, like Maori, call it kumara, deriving from the Quechua word, kumar or another word similar-sounding*.* There are also more clues to indigenous people of Colombia and western South America exploring the Pacific predating the Inca civilization, given the image in this newsletter.
The famous Kon-Tiki expedition of Thor Heyerdahl voyaging to Polynesia from Lima, Peru tried to prove that this contact was not impossible for South Americans and Polynesians. Though, indigenous people had to take more precaution since they didn't carry forecasting devices and radios that Heyerdahl had.
Here, we can conclude that there were very well some Native Americans associating the Pacific Ocean as a mystery, mythological or exclusive for explorers to only know what was out there.
So, yes, only explorers like Yupanqui, an elite and soon to be crowned as the next Sapa Inca (ruler), got to know about what was upon ocean.