When Vikings traveled up rivers to trade and raid, they did so in a succession of different kinds of boats built for the different stages of the river. Their longships were lightweight enough that they could be rowed remarkably far upriver, but eventually the Vikings would have to get into smaller, shallower boats when the river became too narrow and shallow for the longships. And if they ventured far enough inland that even those boats were too wide and deep, they’d switch to dugout canoes made from a single tree trunk. Any of these lighter boats could be carried overland by the Vikings to get from one river to another, or to avoid dangerous sections of a river.
Beginning in the tenth century, the Vikings also built specialized cargo ships that were much bigger than their longships. Unlike the slender longships that were built to maximize speed, these newer cargo ships were broader, and therefore slower due to increased wind resistance, in order to be able to carry heavier loads.
Viking cargo ships could carry no less than five to sixty tons of goods. Since they could transport more goods than their predecessors, they could do so for a lower cost, and were therefore highly advantageous for trade and transportation, the latter especially including ferrying people, livestock and supplies to and from the Viking settlements in the North Atlantic islands.
Norse cargo ships were dependent their sails; they may have had a few oars for maneuvering, but not enough to really propel the ship. They were designed to be manned by a small crew, which left more room to carry cargo. As if to emphasize this purpose, the cargo was covered by water-resistant skins, while the crew was exposed to the elements – but then again, this was also the case for people and goods aboard Viking longships.