Deep currents are driven by differences in ________ of ocean water.

Deep currents are driven by differences in ________ of ocean water.

• A. Temperature
• B. Density
• C. Salinity
• D. Pressure

Answer: (B)

Density differences in seawater drive deep currents. Water becomes denser when it is colder and when it is saltier, so cold, salty water sinks in polar regions and spreads along the ocean depths. This sinking initiates a global circulation—the thermohaline circulation—that moves water and heat across the oceans. Temperature alone wouldn’t fully explain the deep flows, and salinity alone misses how temperature also boosts density. Pressure differences can influence movement locally, but they aren’t the primary driver of large-scale deep-ocean currents.

Density differences in seawater drive deep currents. Water becomes denser when it is colder and when it is saltier, so cold, salty water sinks in polar regions and spreads along the ocean depths. This sinking initiates a global circulation—the thermohaline circulation—that moves water and heat across the oceans. Temperature alone wouldn’t fully explain the deep flows, and salinity alone misses how temperature also boosts density. Pressure differences can influence movement locally, but they aren’t the primary driver of large-scale deep-ocean currents.