Characteristics
Overview
Water with a high salt content. Consuming will damage your health.
Turn it into fresh water before it goes anywhere near your mouth. Salt water is what fills a bottle or bucket when you dip it in the sea, and drinking it damages your health instead of fixing your thirst.
Watch out
Fresh spawns on the beach make this mistake the most. You are thirsty, the ocean is right there, you fill up and drink, and you lose health you could not spare.
The cheap fix is a water purifier set over a campfire. Pour the salt water in, keep the fire fed and drinkable water collects inside. It is slow, but on a coastal base it still beats a walk inland to a river every time you get thirsty.
Groups with electricity go bigger. A water pump sitting in the sea collects water while it has power, and a powered water purifier on the same line cleans it, so a big farm and a water barrel never run dry. Most farmers run everything through the purifier before it reaches a planter; it costs nothing to play it safe there.