One of the most frequent questions we hear at Cruise Critic is "How fast does a cruise ship go?" Cruise ship speeds are measured in knots; 1 knot equals about 1.15 miles per hour. The average speed of a modern cruise ship is roughly 20 knots (23 miles per hour), with maximum speeds reaching about 30 knots (34.5 miles per hour).
How fast a ship is able to sail depends on several factors, including the power of its engines, the weather and the conditions at sea. Ships might have to sail at higher speeds to outrun potential storms or rough waters. Conversely, they might sail more slowly if they find themselves in choppy swells.