| Characteristic |
| Ecosystems |
|
| Inland water | Estuarine | Marine | |
| Nature of water | Freshwater | Transitional/brackish waters (a mix of freshwater and saltwater) | Saltwater |
| Connection to the ocean | Absent; no direct, existing connection to the sea | Present; connected to the ocean, either permanently or temporarily | Present; are part of the open ocean |
| Marine exchange and/or tidal influence | Absent | Present | Present |
| Level of biodiversity | Lower | Moderate | Higher |