The color of the ocean is blue because the water absorbs colors in the red part of the visible spectrum. The blue color is then scattered more than the other colors because it travels in smaller and shorter waves. This is why the sky is also blue because the small oxygen and nitrogen molecules scatter the blue color across the sky during the day.
The ocean looks blue from above because the blue color is being reflected back up at us from the surface of the water.
Sunlight comprises all the visible spectrum colors: red, orange, yellow, green, blue, and violet. When sunlight hits the ocean, water molecules absorb some of the sunlight. Green, yellow, and red are absorbed more than blue and violet, which are scattered or reflected back into the atmosphere. This is why the ocean looks blue.