Cabbeling
![Visualization of cabbeling in an example Temperature-Salinity diagram. Combining water masses A and B in equal proportions forms water mass C, which has a higher density than either A or B.](/Images/godic/202501/02/TS_Diagram2001.jpg")
Cabbeling is when two separate water parcels mix to form a third which sinks below both parents. The combined water parcel is denser than the original two water parcels.
The two parent water parcels may have the same density, but they have different properties; for instance, different salinities and temperatures. Seawater almost always gets more dense if it gets either slightly colder or slightly saltier. But medium-warm, medium-salty water can be denser than both fresher, colder water and saltier, warmer water; in other words, the equation of state for seawater is monotonic, but non-linear. See diagram.