Water is a transparent liquid that has an inherent blue hue. Although small amounts of water appear colorless, large enough bodies exhibit the tendency of the compound to absorb visible red light wavelengths and return slight blue wavelengths.
The blueness of water depends on the depth of an observed area of the liquid. Oceans, for example, are thousands of feet on average and exhibit a strong blue color. The suspension of particulate matter, organic and mineral alike, help scatter light wavelengths and contribute to the blue color. The other color tint of some bodies of water, like green or gray, are contributions of minerals like dissolved limestone, tannins or algae.