Water, water everywhere.....hopefully.

I am creating a series of islands, I do this by creating a large sea then rising the island out of it.
Creating the area required is easy but not so painting it with water, there has got to be a better way.
Any suggestions please?

You could do it just the opposite, and make the islands rising up from a flat baseboard, then paint the flat baseboard island shore outline with a sand and sea color paint, then place real "water" overall, then sink the sea floor around the islands.

There are several islands HOG blank routes on the DLS by fishlipsatwork

Someone was going to make a trans-atlantic chunnel route, connecting the US to Europe, I wonder how that turned out ?

Paint an area, copy-paste.

Water painting is not required where it is deep as the water colour hides it. I only paint near the shore.