The document provides information about Viking longships, including: - Their design allowed them to be strong, lightweight vessels that could sail quickly and also be rowed up rivers and beaches for attacks. - They were clinker built with overlapping wooden planks caulked with tar and animal fat to make them waterproof. Large sails and rows of oars provided propulsion. - Longships ranged in size but some had up to 70 oars and were expensive to build, indicating they were only used by wealthy Vikings like kings. - Distinguishing features included a dragon or animal headed prow and stern, hanging shields, and the ability to sail into shallow waters.