Cargo ships travel at 12 to 20 knots on the open sea. The speed varies depending on the kind of cargo and the company that owns the vessel.
Cargo ships move slowly at sea so as to help preserve power and contribute to green initiatives. Shipping companies are required to keep their vessels traveling at a maximum of 20 knots according to international laws, but some businesses choose to run on much lower power levels in order to conserve more fuel. The speed reduction means goods can take longer to arrive but the cost savings on transportation helps balance out expenses for the boat and consumers.