| Unit name | Description |
|---|---|
| Oligohaline Water | Salinity (PSS) < 5 |
| Mesohaline Water | Salinity (PSS) 5 to < 18 |
| Lower Polyhaline Water | Salinity (PSS) 18 to < 25 |
| Upper Polyhaline Water | Salinity (PSS) 25 to < 30 |
| Euhaline Water | Salinity (PSS) 30 to < 40 |
| Hyperhaline Water | Salinity (PSS) = 40 |