SDI Open Water Scuba Diver Practice Exam

Do longshore currents always move in the same direction as prevailing offshore currents?

1. True

2. False

3. Only during storms

4. Only during high tide

The correct answer is: False

Longshore currents do not always move in the same direction as prevailing offshore currents. Longshore currents are generated by waves approaching the shore at an angle, which causes water to move parallel to the coastline. The direction of these currents can be influenced by various factors, such as the angle of wave approach, local winds, and coastal topography, leading to variations in direction that may not align with the directional flow of offshore currents. In contrast, prevailing offshore currents are influenced by larger oceanic circulation patterns, which can be driven by global wind patterns and the Earth's rotation. Therefore, while there may be situations where longshore currents coincide with the direction of offshore currents, it is not a consistent relationship, and they can and often do move independently of each other. The other options imply conditions under which such a relationship might hold true, but they do not reflect the general and consistent behavior of longshore currents, clarifying that the movements of these currents are influenced more by local conditions than by offshore prevailing currents.