If water is colorless, why is the ocean blue? 🌊 - Water molecules and sunlight Short answer: the more water there is, the bluer it is - Salts and seaweed Seawater's color varies from purple-blue to yellow-green or even red, all because of the different salts and seaweed tinting the water. The more salts and seaweed it contains, the deeper its color is. - How deep the sunlight goes So why does water in a glass stay colorless? The sunlight in it goes through just a few centimeters of water, where