What causes the colour of oceans to vary?

The colour of oceans varies due to factors like water depth, the presence of algae, and the scattering of sunlight. Clear water appears blue because it absorbs red and yellow wavelengths more effectively, scattering blue light. In shallow areas, the seabed or suspended particles can give the water green, brown, or turquoise hues. Algal blooms may cause a green or red tint, while sediment from rivers can make the water appear murky or brown.