Explore how salt concentration affects water density and buoyancy.
Average ocean salinity is ~35 ppt (parts per thousand). Higher salinity = higher density = more buoyancy. Fresh water (0 ppt) has density ~1.000 g/cm³. Seawater ~1.025 g/cm³. Temperature also affects density — colder water is denser. The halocline is the boundary layer where salinity changes rapidly with depth. Thermohaline circulation drives deep ocean currents.