The Viking longships traveled through rough seas better than earlier ships primarily because they were lighter, more stable, and had sturdier construction.
Viking longships were designed with a shallow draft, allowing them to navigate in both open seas and shallow rivers. Their construction used overlapping planks, which provided strength and flexibility, enabling them to withstand rough conditions. Additionally, their design allowed for a balance between speed and stability, making them well-suited for the challenging maritime environments they encountered.