What causes the ocean to appear blue?

The ocean appears blue because water absorbs colours from the red end of the light spectrum more efficiently than blue. The blue wavelengths are scattered, reflecting back to our eyes. The intensity of the blue colour can vary depending on the angle of sunlight, the depth of the water, and the presence of particles or algae. In shallow areas, green hues may dominate due to chlorophyll in algae, while clearer waters appear a deeper blue.