Vikings had a long history of naval trading, which eventually developed into coastal raiding. The longboat was a fast warship about 80 feet long. The ships could be rowed or a single mast stepped amidships with a square sail. The maneuverability, high speed and shallow draught allowed the ships to penetrate rivers, which the Vikings used to attack even inland towns. While bulkier vessels could only be moored in a harbor, the longboats could be beached right on the shore. The flexible hull allowed the longboats to traverse the treacherous waves of the North Atlantic, while still loaded down with goods and warriors. Viking chieftans were even buried in their ships.