Viking longships

The Vikings were from Scandinavia.

The Viking longship is from the humble canoe, the Vikings used these to travel along rivers for it was faster than moving on land.

Through forests and mountains, it was an "easy" ride to take rivers, the first of the canoes, was made with a tree log, with the insides hollowed out to make the inside of the small boat and used oars, overtime they added planks to the log boat, using the clinker or lapstrake method, instead of it being a log boat, it was a layered hull.

as the Roman empire expanded north, some Scandinavians joined the Roman armies and brought back to Scandinavia, roman maritime technology. 

As the Romans used Sails to move boats instead of rowing and had large warships that controlled the sea, and cargo ships that ferried goods along the waterways.

Now the "newer" Viking longships used anchored oars, basically locking the oars to 180 degrees of movement, making the boats more efficient, before working with the Romans, the Vikings used cloth and sewing to bind the wood pieces together, but after working with the Romans, they started to used iron nails instead. 

They removed the wood log origin for a keel wood plank. But the strength of the boat did not come from internal beams and planks but relied on the strength of the outer shell of the ship. The boat which was made with keel wood was faster than the Roman warships.

As sails were expensive, they did not use sails.

Then the Roman empire collapsed.

By the 8th century, the idea of a sailing ship was proposed, as it would be used for long-distance travel, they added sails to this new "sailing ship" and the speed that the boats traveled was the quickest in their fleet, and then the "Viking Longship" was created. 

The longships could carry 100 Vikings to battle, and the ships were used to travel along seas, and big rivers, if need be the ships were light enough (in weight), to carry over land. 

The bigger ones were used in large sea expeditions, and the smaller ones were used for fishing.

The Vikings sailed west and were able to travel to North America and they set up multiple settlements centuries before any European was able to reach.