What is the most abundant metal in sea water

Answer 1

I suspect Mg ion

Answer 2

a google search turned up data showing that Na is about 8 times the concentration of Mg. (by mass)

So, since Na is lighter than Mg, it would be even more abundant, counting the number of atoms present.

Answer 3

I sort of consider NaCl as defining salt water :)

Answer 4

Hmm. Hadn't considered that take on it. You may be right...