There is no simple answer to the question "What Color is the Sea?" because it depends on a range of elements, such as the weather, the depth of the sea, how much wave action there is, and how rocky or sandy the coast is. The sea can range in color from bright blues to intense greens, silver to gray, foamy white to polluted slick.
The four photos above are all of the same small stretch of coastline, but look how different the color of the sea (and sky) is in each. They clearly show how the weather and time of day can change the color of the sea dramatically.
The top two photos were taken around midday, on a sunny day and on an overcast day. The bottom two photos were taken not longer after sunrise, on a clear day and on slightly cloudy day. (For larger versions of these photos, and several more taken of the same stretch of coastline, see the Seascape Reference Photos for Artists.)
When you're looking at what color the sea is, don't look at only the water. Also look at the sky, and consider the weather conditions. If you're painting on location, changing weather can have a great impact on a scene. It also influences which paint colors you select.
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:
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.
One of the meanings of the term study is "practice piece" (it can also be used for an experiment to test composition, or a quick painting to capture the essence of a scene for later work). The reasoning behind doing a study, rather than a full or 'real' painting, is that you focus on one particular aspect of a subject, and work at it until you get it 'right'. Then when you do start the bigger painting, you (in theory) know what you're doing. This saves the frustration of struggling with a small part when you want to be working on the whole painting, and means you never end up with one section of the painting overworked (which can can look incongruous).
The small sea study shown above was painting on location, or plein air. Although I had an array of colors available (see list), I used only Prussian blue, cerulean blue, cobalt teal, and titanium white.
Prussian blue is a favorite of mine and is a very dark blue when used straight from the tube, but quite transparent when used thinly. The section behind the wave, and the lower half of the wave, were painted with Prussian and cerulean blue. The top section of the wave was painted using cobalt teal, and the wave foam with the titanium white. The darker blues show through the lighter wave colors because I was using the paint thinly (glazing) in places, blending in others, and applying it quite thick where I wanted solid color.
The aim of this study was to get the angle of the wave and the change in color on the wave right, as well as to create a feeling of moving water. Having got that working to my satisfaction, I could then focus on painting a wider seascape.
A lot of the difficulty with sea painting comes from the fact that it's constantly moving. But understanding the elements, such as the different types of sea foam, helps simplify what you're looking at.
Surface foam floats on the water, moving up and down as the wave passes underneath it. If you have trouble visualizing this, think of the wave as energy that moves through the water causing ripples, like when you flick a blanket on the edge and a ripple moves through the fabric.
Surface foam typically has holes in it, rather than being large, solid area of foam. This pattern can be used to lead a viewer's eye through the composition, as well as to create a feeling of movement or height in a wave.
Wave foam is created when the weight of water at the top of a wave becomes too heavy, and it breaks, or falls over, at the crest of the wave. The water becomes aerated, creating foam.
One of the fundamental composition decisions in a sea painting is selecting the position of the shore, and thus the direction the waves which run parallel to the shore. (There are exceptions, of course, caused by local currents, rocks, strong wind.) Is the shore at the bottom of the composition and are the waves thus coming in directly towards the viewer of the painting, or does the coast meander up the composition and thus the waves are at an angle to the bottom edge of the composition? It's not a question of one choice being better than the other. Just that you need to be aware that you have got a choice.
Make a decision about this, then ensure that all the elements you paint (waves, open sea, rocks) are consistent in direction according to this, all the way into the distance.
When painting waves by observation rather than from imagination, look to see how much reflection there is on the wave. You may see reflection from both the sky and from the wave itself. Just how much will depend on local conditions, for instance how choppy the sea is or how cloudy the sky is.
The two photos above show very clearly how the blue from the sky is reflected on the surface of the water, and how the wave foam is reflected on the front of the wave. If you're wanting to paint realistic waves or seascapes, this is the kind of observed detail that will make the painting read 'right' to a viewer.
The principles about direction of light in a painting and the corresponding shadows that are cast also apply to waves. The three photos here all show a wave that's approaching directly onto the shore, but in each the light conditions are different.
In the top photo, the light is shining at a low angle from the right. Notice how strong shadows are cast by parts of the wave.
The second photo was taken on an overcast or cloudy day, when the sunlight was diffused by the clouds. Notice how there aren't strong shadows, and how there isn't any reflected blue on the sea.
The third photo was taken on a sunny day with the light shining from behind the photographer, onto the front of the waves. Notice how little shadow is visible with such a front lighting situation.