Why Is the Ocean Blue If Water Is Clear?

Tropical blue ocean in Hawaii.

If you look at water in a glass, it looks clear. When you look at water in a lake, pond, or ocean, you will see varying shades of blue and green. Why does this occur in large amounts of water, but not in small amounts? Much of the color variation has to do with how light is absorbed by the water. Another factor is what is in the water.

Understanding how light interacts with the water is the best way to learn about the water’s ever-changing colors. Smaller amounts of water will not scatter light in the same way as large bodies of water. You will also need to understand that water will change color if certain organisms are present.

So Why Is the Ocean Blue If Water Is Clear?

Ocean water appears blue because it is able to absorb the other colors in the light. Colors like green and red are absorbed so they don’t show up. Since the blue light is scattered and collides with the water molecules, the water appears to be blue.

Light is made up of all the different colors that make up the rainbow. Each of the colors has its own pattern or wavelength. Due to how the molecules in water are formed, the blue light cannot be absorbed like the other colors. In areas where the water appears to be green, some of the green light may be scattered as well.

Blue color light reflection on water surface

Why Does the Ocean Look Blue?

Water is basically a filter for sunlight. Since the colors that belong to the spectrum where red is prevalent are easily absorbed by water, the colors that aren’t absorbed are reflected back. This filter eliminates the reds and leaves the colors in the blue portion of the spectrum visible.

If you look at the ocean in various parts of the world, the amount of blue that is visible is different. Some areas have a deep blue color, while others show a much lighter, almost sky blue. While most of this is due to the refraction of light, some of the colors are caused by what is in the water.

Why Are There Different Shades of Blue and Green in the Ocean?

Waves on the green ocean water.

The wavelengths that make up the colors in sunlight are different. Red ones are much longer than blue and green wavelengths. Because the shorter ones are able to scatter closer to the surface than the longer ones, red and orange are not normally seen in the water.

Instead, different hues of blue, green, and sometimes, purple may be seen. As you go deeper into the water, it can become very dark. This is because all of the light is being absorbed into the water. With all of the light being taken in, very little is left to scatter.

What Makes the Ocean Water Appear Clear in Some Areas?

Much of the color in ocean water comes from how the water is reflected from the bottom. In areas where the bottom is very shallow, the water may look as if it is crystal clear. As light passes through a glass of water, there is nothing to stop it. There is no depth or particles to slow it down.

In the ocean, however, the water will appear blue if the light does not reflect back up from the bottom. Very shallow water may have no color at all and give the impression that it is very clear.

Diver floating in shallow water.

Why Is the Water near the Bahamas Light Blue?

The water around the Bahamas is very shallow. It also lacks sea vegetation or plants. If more vegetation were present, the water would appear to be much greener. The light blue color of the ocean water is primarily due to how shallow the water is in many areas near the beach.

As you begin to move out toward the open sea, you will notice the color of the water starts to change to a deeper, more vibrant blue. There are also areas where the water will begin to look green. The sea vegetation disrupts how the light is scattered throughout the water and will cause it to change colors depending on how many plants are present.

Why Does the Water near Hawaii Look Clear and Clean?

Blue ocean wave on a bright sunny day.

The water that surrounds the Hawaiian islands is often a brilliant blue. In some areas around the islands, the water is crystal clear. Where the water is clear, it is also very shallow. The white sand of the beaches provides a beautiful contrast to the blue of the water. Where the water is clear, it is easy to see through it to the sandy bottom.

Much of the sediment that lies along the bottom of the ocean near Hawaii is made up of volcanic ash. This is heavier than other types of sediment and will take much longer to get it stirred up. When it has been disturbed, it can turn the water dark and make it look murky and unclean. Once the sediment begins to settle, the cloudiness will go away.

Another reason why the water around the Hawaiian islands is so beautifully clear is due to all of the coral reefs that surround them. The reefs are living creatures and have their own ecosystem. The reefs have a way of keeping themselves clean and reducing the amount of sediment that gets stirred up.

What Makes the Sand on Certain Beaches Different Colors?

Pink sand beach in the afternoon.

The sand on a beach is made up of a variety of rocks and minerals. The structure of the crystals will determine what color they appear to be. Beach sand can be almost any color, including pink, red, black, green, and white. The mineralogy of the sand will tell you much of what you need to know when it comes to determining why sand is a particular color.

Red sand has normally been exposed to or contains some degree of iron. Orange sand may be a combination of broken shells and limestone. Each color corresponds to a mineral or element that can be found in the sand itself. White sand has an abundance of quartz crystal fragments and will normally be free of contaminants.

Does Pollution Have an Impact on the Color of Ocean Water?

If water is heavily polluted, you may see some level of discoloration when it comes to the blue tint of the water or how clear it is. When the water is stirred up, it may have a brown or dark gray tint to it, but in most cases, pollution will not drastically impact the color of the water.

The ocean has a way of cleaning itself as it works through its cycles. Water from deep down in the ocean makes its way to the top while the surface water settles to the bottom. This helps to settle any dirt or debris that is disturbed by the waves or creatures that move through the water.

Does Salt Have Anything to Do With the Color of the Water?

Rocky mountain surrounded by blue ocean and coral reef.

Salt is just one type of organic matter that can change the color of ocean water. In most cases, salt is white, but it can be found in other colors as well. The color of ocean water may be a yellow, green, brown, or blueish color. The color will be determined by the different types and amounts of organic matter that have been dissolved by the water.

Vegetation can turn the water green or yellow, while brown may be the result of sediment or ash being stirred up by creatures that live on the ocean floor. As the sediment begins to settle, much of the cloudiness will start to disappear and the water will return to its blueish-green color.

Does Temperature Cause the Color of the Ocean to Change?

The warmer the water in the ocean, the bluer it will appear. As the water becomes warmer, the phytoplankton and much of the marine life will begin to move towards cooler waters. The increase in acids that are often present in warm water will give the ocean a much deeper blue color than water found in cooler climates.

Individuals who are studying climate change believe that as the oceans begin to heat up, the color of the water will undergo some dramatic changes. Most believe the oceans will be much bluer in the future due to the warmer temperatures.

Now You Know Why the Ocean Is Blue

White sailboat floating in the blue ocean

The color of the ocean’s water and the beaches along the shore will depend on where you are and what is going on in the water. The temperature of the water and the mineral makeup of the sand on the beach will also play a role in determining how blue the water appears.

Look closely at what is surrounding the area. Coral reefs and other underwater formations will definitely play a role in how the water looks from above. Most coral reefs are surrounded by crystal clear water and bright, white beaches. They are also located in shallow areas of water, which also plays a role in how clear the water may appear to be.