Nature gives the world so many variations of force and climate. Think of the tides, rain, snow, wind, ice, hurricanes and typhoons. Let us now consider the forces involved in those of the ocean currents.
For the United States there are two main currents: the Gulf Stream coming from the Gulf of Mexico, and the California Current in the vicinity of San Francisco and Los Angeles. These ocean currents are created by the rotation of the earth.
The better known of the two is the Gulf Stream which flows westward through the Caribbean Sea, thence northeast past Florida, up the east coast of the US, and eventually completes a full circle of the Atlantic Ocean, returning to the Caribbean.
The forces involved allow this initially warm water to drift thousands of miles, to the extent that because the water temperature is still above freezing, even around the United Kingdom and the coastal regions of Europe in winter, there is no sea ice and thus all the ports in those regions are able to remain open year-round.
In the sailing ship days, once sea current forces were recognized, mariners used them to their advantage when making passage. Even today in motor ships, captains may utilize currents to allow quicker passage time to the next port so they can arrive earlier than scheduled and reduce the consumption of expensive fuel.