Water density within Commander 1.3

[Paul Riley]

After playing around with Commander for a while,which is great mind you,I am interested in the water density section.For each score ie 1.2.3 and so on what would each score represent? eg,1 may represent 1m?,even though it probably doesnt.
I think jimbuna mentioned somewhere that vis. could be as high as 50m in some places?.
Other than particular areas of the world,what else could affect water density/vis?.

Thanks.