How salty is seawater?

The level of salt in water is generally expressed in parts per thousand (ppt), with freshwater having <1 ppt, seawater/saltwater having >30 ppt, and brackish water, 1-29 ppt (or everything in between freshwater and saltwater).

(adapted from Gary Kraemer, DNREC, “Background Information for Interpreting Water Quality Monitoring Results,” water quality arrows…ppt)