We lack a sea, I'm going to suggest a few for us to debate.
-Mercury
-Bromine
-Magical liquid
-Alcohol
-Water (Obvious)
-Gelatin, this would probably be a living sea.
-A very heavy gas, perhaps argon will get a usage.
In order:
-Eh. A bit on the rare side, in the crust area. Not too terrible; I won't oppose it if it's popular, but I certainly won't support it.
-See Mercury.
-No.
-A bit...off. It's an organic chemical, after all; out-of-place in a world of silicon. Moreso than it would be otherwise, I mean. Maybe Si
2H
6O or something.
-Perfectly fine. Common, contains generally-useful elements for life.
-...
-A bit vague. For argon: See bromine.
EDIT FOR GM:
Water has my vote.
We lack a sea, I'm going to suggest a few for us to debate.
-Mercury
-Bromine
-Magical liquid
-Alcohol
-Water (Obvious)
-Gelatin, this would probably be a living sea.
-A very heavy gas, perhaps argon will get a usage.
I vote for lesser liquid mana (as in diluted form) but what would the pros and cons be for the others?
Pro: Not absurdly expensive. Makes sense.
Con: Not absurd.