Did the Aztecs, Mayans or Caribbean people have any naval activity more ambitious than fishing boats? Did the Central American empires conduct trade with the Islanders or with the people living in what is now the US gulf coast? Do we know what their boats looked like? Do we know if voyages across islands or to/from the mainland would have been exceptional, one off ventures or routine trips?
The mountainous, jungled terrain of inland Mesoarmerica was understandably a hindrance to land travel; it was further complicated by the mosaic of shifting polities during the Pre-classic and Classic periods. A trade route through a neutral market center could easily be disrupted when the town allies itself with the rising city-state of the day. There is plenty of evidence suggesting that coastal trade of elite or exotic goods (salt, obsidian, textiles) was common or even preferred. Many sites along the coast of southern Belize have been identified as potential trade hubs with links all the way to Chichen Itza. On the western coast, a Late Classic sea trade route for metals between Oaxaca and Jalisco has been proposed. Colonial reports do indicate that coastal trade was active at the time of the Spanish arrival, carried out in dugout canoes.
Sources/further reading:
Preclassic Obsidian Procurement and Utilization at the Maya Site of Colha, Belize David O. Brown, Meredith L. Dreiss and Richard E. Hughes Latin American Antiquity , Vol. 15, No. 2 (Jun., 2004)
Hosler, Dorothy, and Andrew Macfarlane. "Copper sources, metal production, and metals trade in late Postclassic Mesoamerica." Science 273.5283 (1996)
Plus anything from LSU's Heather McKillop, she writes quite a lot on this topic