Can water float by water?

Gibraltar Strait, the Strait of Hormuz, etc. It can be seen that the deep salty seawater flows downwards, but the surface layer flows in the opposite direction.

Have you ever seen water freeze in winter? What's it like under frozen water? All the way up, the bottom is stable at 4 degrees Celsius.

There are generally two places with serious river pollution, one is the sewage outlet in the middle and upper reaches, and the other is the river estuary. The latter reason is that seawater jacking causes pollutant concentration.

The above three examples are typical of the buoyancy of typical water.

When two groups of water with different properties meet, the lighter group climbs obliquely along the interface and the other group climbs downwards, which is the process of buoyancy. The lighter water mass replaces the heavier water mass, and its volume is larger than its own gravity, so it floats (buoyancy is equal to the gravity when the water mass finally stabilizes), while the heavier water mass sinks.