An interactive visualization demonstrating why freshwater from SGD flows out over the denser saltwater rather than sinking into it.
Learn MotionWhy Oceans Don't Drain Into the Ground
Submarine Groundwater Discharge (SGD)
Why Freshwater Floats on Saltwater
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Now, let's look at what happens when this freshwater hits the ocean. You might wonder if the heavy ocean water could push back and flood the groundwater. It can't, because of density. Freshwater is lighter than saltwater. In this simulation, you can adjust the freshwater flow. Notice how the fresh water always stays on top, forming a plume that floats over the denser saltwater. This creates a natural barrier. The saltwater cannot easily sink down into the freshwater aquifer because it is heavier. This density difference is the key reason why the ocean doesn't drain into the ground.
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