Originally posted by Rhapsody:

"The open surface waters of the Baltic Sea "proper" generally have a salinity of 0.3 to 0.9%, which is border-line freshwater." from Wikipedia, so it's pretty good. Don't know how it affects brewing chemistry, but as I said, rainfall also exists in the game.

Yeast are single cell eukaryotic micro organisms. Salt kills them. A high salt content will kill them all. A low salt content kills some of them and slows down the fermenting process. That's why you have to add salt to bread, to slow down the yeast growth. There has to be some fresh water in game or you couldn't make bread from barley flour. You would only be able to make flat bread or pan bread that you would use for something like Fish wraps.

That said any civilization that can ferment and can smelt metals can make a still which will not only distill spirits but can make fresh water out of salt water.

There is rain and snow in game so there has to be fresh water and the technology for cisterns and aqueducts existed back in the Viking age. My personal view is that there is no salt water in Valheim. Its all fresh water. Yggdrasill is fed by 3 wells which have to be fresh water wells to support an ash tree. The other supporting point is swamps. All the swamps in Valheim have to be fresh water swamps because the trees in the swamp have fresh water root systems and not the tangled mess of the root systems of mangrove trees that are found in salt water swamps.

Another clue that it is all fresh water is the tin deposits in game. They are all secondary deposits found on the coast and river channels. These deposits are colluvial deposits caused by fresh water flowing over primary deposits and causing the cassiterite to form residual concentrations that become secondary deposits.

Another potential clue is that salt isn't a food in game. There are no salt deposits to mine. None of the foods are preserved with salt. They are cooked/smoked. If the oceans were salty there would be salt deposits all over the place. What little salt that exists in game is from other food sources. Our Vikings are likely getting all the salt they require from the carrots, turnips, onions, boar, wolf, and lox meat in their diets.

Some of the fish found in Valheim's oceans are exclusively fresh water fish (pike, perch, tetra) that can't survive in salt water. Most of Valheim's salt water fish (Angler fish, tuna, some species of cod, some species of grouper, some species of puffer fish, herring, and salmon) can live in fresh water and some have to return to fresh water to spawn. Made up fish like the trollfish and magmafish can be what ever the devs want them to be. This could mean that all of the fish in Valheim are fresh water fish. Even eels (and therefore sea serpents) and turtles (and therefore leviathans) can survive in fresh water.

The only thing that I can think of that requires a salt water biome to survive in game is a barnacle. Perhaps only the deep waters in Valheim are salty or the fictitious abyssal barnacle is an unknown species of fresh water barnacle.