Most Americans lived close to the Atlantic Ocean. The sea had long been essential to American prosperity. It remained the quickest and easiest highway between the colonies in an era when it was cheaper to ship a ton of goods to London than a few hundred miles overland. New England was a major shipbuilding center. In 1770, Americans were responsible for the launching of one-third of the British merchant fleet. More than 33,000 Americans made their living from the sea. Because of hostility to the British policy of forcibly impressing sailors into the British navy, American seamen were overwhelmingly Patriot in their sympathies. The American colonies at the outset of the war had men ready and willing to take the war to the British at sea. What they lacked were the resources and organization necessary to challenge the most powerful navy in the world.

Before the end of 1775, George Washington had created a small naval force to harass British merchantmen carting supplies to Boston. Many states commissioned warships to guard their waters. The official birth of the United States Navy came on October 30, 1775, when Congress voted to raise naval forces to help defend the “United Colonies.” A short time later, Congress authorized the formation of a corps of marines. America's fledgling navy was supervised by a congressional committee, and John Adams wrote the first Rules for the Regulation of the Navy.

From its inception, the navy was hampered by a wide range of problems. One was the intrusion of politics into the selection of the officers. Here the situation mirrored that of the army, but the consequences were more deleterious. Commands went to men from influential families or to those who came from the towns that outfitted the ships. Talented outsiders like John Paul Jones had to struggle to get ships of their own. Manpower was also a problem. Plenty of seamen were available, but most preferred the easier and more lucrative life aboard privateers to service on the harsher terms of the navy. The crews of Continental warships were heterogeneous collections of foreigners, released British prisoners, and other societal outcasts. Sailors of eleven nationalities composed the crew of John Paul Jones's Bon Homme Richard.

Commodore Esek Hopkins commanded the first American fleet. In early 1776, he led eight ships on a raid of Nassau in the Bahamas. On the way back the fleet intercepted a smaller force of British ships, which outfought the Americans and slipped away. The expedition to the Bahamas was an exception to the normal course of American naval operations. The United States Navy concentrated on commerce raiding, with single ships prowling the Atlantic shipping lanes and the West Indies. Over the course of the war, Congress bought or built fifty to sixty ships, a number of which never got to sea because of the British blockade and raids on American ports. After 1778, many in Congress believed that the availability of French naval power reduced the need for a strong American navy. By the end of the conflict, the navy had been reduced to two ships.

The United States Navy was too small to challenge the Royal Navy or to interrupt British commerce. Far more destructive to the British war effort were the depredations of American privateers. These were privately owned and operated ships that were issued letters of marque from Congress or one of the states authorizing them to attack British shipping. Privateers were allowed to keep or sell everything they captured from the enemy. Outfitting a privateer was a risky — but potentially highly lucrative — investment. Privateers preyed on lightly armed merchantmen or transports, always attempting to evade British warships.

The privateers caused Britain real economic pain. The British admitted to losing 733 ships by early 1778. The Royal Navy responded by organizing convoys across the Atlantic and by tightening the blockade on American ports. Despite this, 400 privateers set sail in the second half of the war. By the end of the conflict, Britain had lost 2,000 ships and cargoes worth more than £18 million. Around 12,000 British sailors were captured. The Royal Navy commanded the seas, but it could not prevent militant American entrepreneurs from making the trade lanes so dangerous that it became hard to insure British ships setting off to sea.