First of all, a small note - The Aztecs lived in what is know Mexico City, which is either in North America or in the northern part of Mesoamerica depending on how you define it. The Inka lived in the Andes mountains of South America.

The Inka (by which I mean indigenous Andean peoples more generally) did absolutely undertake at least some coastal voyages. Rafts were common along the coast of South America as far north as (at least) Ecuador and as far south as Chile. The Spanish word "balsa" meaning raft, eventually became the trees that local people made their rafts from. Even though relatively few of these rafts survive in the archaeological record, we know about their existence from two sources.

Firstly, the Spanish documented them. In 1526, Pizarro's ship pilot captured a large balsa raft and kidnapped several of the native sailors to serve as interpreters. He described the raft as being manned by approximately 20 sailors, and being filled with "many silver objects, tiaras, crowns, bands, tweezers and bells... all of this they brought to exchange for some shells." (Dewan and Hosler 2008, ultimately citing Xerez's Verdadera relación de la conquista del Perú (1534))

Secondly, we know that spondylus shells, which live only in the warm waters off of Ecuador - are found all across the Andes at sites dating back thousands of years. They were ritually important and so some sort of Spondylus trading economy appears to have been in place by 100 BCE. Spondylus is found across the highlands from this period, and it continued to be ritually significant all the way up to the Spanish conquest 1600 years later.

So, coastal trade within the Andes very clearly happened. But, what about longer distances?

There are theories, based on stylistic similarities and timing, that Andean rafts introduced metallurgy to West Mexico and parts of central America from Ecuador and Colombia around 800 CE. This isn't my area of speciality so I won't comment further unless you have specific questions. There is also a historical account, from the chronicle of Pedro Sarmiento de Gamboa, that one of the Inka emperors may have lead a significant series of voyages around the Pacific sometime around 1480. He supposedly visited either Easter Island, the Galapagos, or both. No significant archaeological evidence has been found that would collaborate this voyage actually took place. However, its inclusion in Sarmiento's account would seem to indicate that Inka informants, living in Cusco, had at least some knowledge of the geography of the Pacific by the 16th century.

Cited:

Dewan, Leslie, and Dorothy Hosler. "Ancient Maritime Trade on Balsa Rafts: An Engineering Analysis." Journal of Anthropological Research 64, no. 1 (2008): 19-40. Accessed May 8, 2020. www.jstor.org/stable/20371179.