Why does the ocean appear blue from a distance?

The ocean appears blue primarily because water absorbs red, orange, and yellow wavelengths of light more readily than blue wavelengths, so blue light penetrates deeper and is scattered back to our eyes. This is an intrinsic property of water molecules themselves, not just a reflection of the sky. The sky's reflection does contribute to the color, especially in calmer conditions, but even on overcast days the ocean still looks blue-green. Depth, dissolved particles, and algae can shift the color toward green or other hues. From a distance, atmospheric scattering also enhances the blue appearance, since shorter blue wavelengths scatter more easily through air before reaching your eyes.