What are ocean currents and how do they affect navigation?

Ocean currents are large-scale movements of seawater that flow through the world's oceans and significantly influence navigation. They are driven by various factors, including wind patterns, the Earth's rotation, and differences in water temperature and salinity. The direction and speed of these currents can greatly affect the performance of a vessel, altering its course and speed depending on whether it is moving with or against the flow of the current.

When navigating, understanding ocean currents is essential for route planning and fuel efficiency. For instance, utilizing a favorable current can enhance a vessel's speed, reducing travel time and fuel consumption. Conversely, when a vessel encounters a strong opposing current, it may necessitate adjustments to the intended course and increase fuel usage. Recognizing these dynamics is crucial for safe and effective maritime operations.

The other options provide definitions or concepts that do not pertain specifically to ocean currents as they relate to navigation. Changes in water temperature, weather patterns that influence wave height, and tides that occur twice daily, while relevant to broader oceanographic phenomena, do not capture the essence of how ocean currents interact with navigation practices.