What is the vertical movement of the surface of a body of water called?

The vertical movement of the surface of a body of water is referred to as a tide. Tides are caused primarily by the gravitational pull of the moon and the sun on the Earth's oceans, which creates a regular rise and fall in water levels. These movements can significantly affect navigation, fishing, and the behavior of marine life near coastal areas.

While currents refer to the horizontal movement of water that is driven by various factors including wind, temperature, and salinity, they do not pertain to vertical shifts. Mean water generally describes an average water level over a period and does not define movement. Sheer, on the other hand, is unrelated to water movement and typically relates to the structural integrity of materials under stress.

Understanding tides is critical for boaters as they must be aware of tide schedules for safe navigation and docking, especially in areas with strong tidal variations.