They were known as sailors, warriors, and explorers.
The Vikings built the finest kind of seagoing vessels both for trade and battle. They were way ahead of their time since they could sail down the breeze then row to windward fast when needed. They were lapstrake planked similar to our more modern fishing dories but often planks were fastened to frames with twine rather than spikes or trunnels (tree-nails usually of locust) as we do now. Look at: