The Gulf Stream is a warm and swift ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida into the Atlantic Ocean. It is probably the most famous ocean current in the world. The Gulf Stream is typically 100 km wide and 800 to 1,200 m deep, and its current velocity is fastest near the surface, with the maximum speed typically about 2.5 m/s. The Gulf Stream is part of a general clockwise-rotating system of currents in the North Atlantic.

The Gulf Stream has a significant impact on the climate of the coastal areas of the East Coast of the United States from Florida to southeast Virginia, and western European countries as well. The warm water transported by the Gulf Stream undergoes evaporative cooling as it travels north, and the cooling is wind-driven. The Gulf Stream influences the climate of the east coast of Florida, keeping temperatures there warmer in the winter and cooler in the summer than the other southeastern states. England is about the same distance from the equator as cold regions of Canada, yet England enjoys a much warmer climate due to the warm water of the Gulf Stream.

The Gulf Stream is caused by a large system of circular currents and powerful winds, called an oceanic gyre. The Gulf Stream was first described by the Spanish navigator and explorer Juan Ponce de León early in the 16th century, and in the late 1700s Benjamin Franklin produced a map of the current. Today, scientists can study the Gulf Stream using various methods.