There's no shortage of options available to a painter when it comes to choosing colors for the sea. A color chart from any paint manufacturer will provide you will the full choice. The photo above (see larger version) shows the range of acrylic paint colors that I have.
From top to bottom, they are:
- Idanthrene blue (Daler Rowney)
- Prussian blue (Daler Rowney)
- Ultramarine (Liquitex)
- Cerulean blue deep (Golden)
- Cerulean blue (Brera)
- Cerulean blue (Winsor and Newton)
- Cobal Turquoise (Winsor and Newton)
- Cobalt Teal (Golden)
- Phtalo blue red shade (Winsor and Newton)
- Phtalo turqoise (Daler Rowney)
- Green Gold (Golden)
- Phtalo green blue shade (Daler Rowney)
But the reason I have so many 'sea colors"' isn't because a sea painting needs so many, rather it's because every now and then I treat myself to a new color and so have built up quite a collection of blues. Painting a small color sample of each as shown in the photo makes it easy to compare the various colors and the opacity or transparency of each.
I have favorite colors that I use often, but like to try out others just to see what they're like. So although I searched through my paints for all the blues to paint the chart shown in the photo, I used only a few when actually painting, as you can see in this sea study.
In his notes, Leonardo da Vinci said the following about the color of the sea:
"Sea with waves does not have a universal color, but he who sees it from dry land sees it dark in color and it will be so much darker to the extent that it is closer to the horizon, [though] he will see there a certain brightness or luster which moves slowly in the manner of white sheep in flocks ... from the land [you] see the waves which reflect the darkness of the land, and from the high seas [you] see in the waves the blue air reflected in such waves."
Quote source: Leonardo on Painting, page 170.