Why Is Hawaii Water So Blue?

The islands around Hawaii have the clearest blue water with visibility up to 200 feet. But why does Hawaii water seem so clear and blue? This article looks at why the ocean water is so blue around Hawaii. If you want to find out, read on!

Several things influence the color of the water in Hawaii. As sunlight enters and interacts with water molecules in the ocean, it absorbs red wavelengths remaining blue wavelengths are scattered, giving the water a blue appearance. The lack of algae and sediment also keeps the water clear.

Hawaii islands are famous for white sandy beaches and sparkling blue ocean waters. You might wonder why the water is so blue and why they aren’t so blue near your local beach. Here we look at the science behind Hawaii’s blue water mystery.

Scattering and Absorption of Light in The Ocean Water

Sunlight light contains photons that have several different wavelengths that include all the colors of the rainbow. Photons with the longest wavelengths are red, orange, and yellow, and photons with the shortest wavelengths are violet and blue in the visible spectrum.

Sunlight will unavoidably be altered when it interacts with a different matter. It depends on what the sunlight interacts with, and some photons will be absorbed while others will remain. That action is called scattering.

When sunlight hits the ocean’s water, it interacts with water molecules, absorbs red light with a longer wavelength, and lets the short blue wavelength pass. This scatters and reflects blue wavelengths in the water, making the ocean appear blue.

Sunlight consists of the full spectrum of colors, from violet, yellow, red, and the rest of the rainbow colors. Sunlight wavelengths differ for each color in the spectrum.

When the sunlight penetrates the ocean water more than a few meters, most oranges and reds have disappeared altogether, leaving the remaining violet and blue behind.

The deeper it goes, the next colors to disappear are green and yellow. Violet and blue have the shortest wavelengths and can penetrate the water the deepest.

When blue and violet wavelengths remain, they are scattered by particles in the water, making the ocean water seem blue.

Just like the scattering of blue light in the sky gives the appearance of a blue sky, the blue wavelengths of light are reflected in the ocean water giving it an appearance of blue water, and that is why the ocean around Hawaii seems so blue.

But light reflection and absorption are not the only factors influencing ocean water’s appearance. Other influences can alter the color of the water, like the presence of algae and sediment.

Phytoplankton / Algae

Phytoplankton is single-celled microorganisms that use green pigments to extract energy from the sun to convert carbon dioxide and water into the organic material that makes up their bodies. This photosynthesis generates approximately half of the oxygen that humans breathe.

All plants on Earth and in the sea use chlorophyll to extract energy from the sun and transform water and carbon dioxide into new oxygen through photosynthesis.

Some particles like the cells of phytoplankton or algae can also absorb some wavelengths of light, which can influence the water’s appearance.

There are other light-absorbing substances in the ocean like chlorophyll, which algae use to produce carbon by photosynthesis that can influence the color of the ocean water.

Because of the green pigment, algae absorb the red and blue wavelengths for photosynthesis and reflect green wavelengths into the water.

Other parts of the ocean in the world with high algae density will have shades of green to blue-green, depending upon the concentration of algae in the water.

The basic assumption behind ocean color is the more algae in the water, the greener it looks, and the fewer algae, the bluer it seems.

Hawaii has fewer algae, organic particles, and zooplankton floating in the ocean water than other regions, making the ocean water around Hawaii seem bluer.

The surface water around Hawaii is also warmer because it is a tropical region with an inadequate supply of chlorophyll, which reduces the number of algae and zooplankton that could influence the ocean’s appearance.

Rotation of the Earth, Ocean Basins, and Sediments

Ocean Basins and Cycles

Another factor to consider that can influence the ocean’s color is when the Earth rotates, the ocean’s water basin rotates the water from west to east, and when this occurs, surface water also moves out.

What was near the shoreline moves out to sea, and the returning water brings in cloudy sediments to the coastline that can affect the water’s clarity and color.

This water rotation brings in organic material and sediments that are the primary cause of murky water. While other coastlines constantly experience cloudy upwelling waves, Hawaii doesn’t encounter the same level of upwelling because the islands are surrounded by coral reefs that protect the shoreline.

These coral reefs around Hawaii withstand and disperse incoming waves’ energy and prevent sediment from being disturbed and dragged up.

Sediment

Hawaii also has less sediment that gets stirred up during the Earth’s rotation. The sediment around Hawaii islands consists primarily of heavy coral skeletons, coarse sand, volcanic rock, calcareous algae, and mollusk shells that are not easily stirred up.

Hawaii needs energetic wave action to stir up the sediment. When the sediment is stirred up during a tropical storm, they remain suspended for a short time because they are heavier.

Much of the sediment stirred up quickly settles back down after a storm passes, and the visibility returns, making the ocean appear more transparent.

Other factors that can influence the ocean’s clarity are runoff from rivers, resuspension of sand and silt from the bottom by tides, waves, and storms, and several other substances that can change the color of the near-shore waters. Because of the calm waters around the Hawaii Islands, the ocean’s clarity is not affected, and it lends a bluer hue to the water.

The reason that the ocean water around Hawaii appears bluer than other coastlines around the globe is a combination of these factors:

Coral reefs surround the islands and, in turn, protect the shorelines from energetic waves.
The sediment in Hawaii waters is heavier and not easily stirred up.
There are less algae in the water due to deficient nutrients in Hawaii.
Water absorbs red light and reflects the remaining blue light when it interacts with water molecules.

Where is The Bluest Water on Earth?

The bluest water on Earth is found in the following places.

Bluest Waters Around the Globe

Hanauma Bay, Oahu, Hawaii.
Maniniowali Beach, Big Island, Hawaii.
Aitutaki Lagoon, Cook Islands.
Ambergris Caye, Belize.
Blue Lagoon, Iceland.
Cala Macarelleta, Menorca, Spain.
Con Son, Vietnam.
Crater Lake, Oregon.
Devil’s Bay, Virgin Gorda, British Virgin Islands.
Egremnoi, Greece.
Exuma, Bahamas.
Five Flower Lake, China.
Havelock Island, India.
Huascaran National Park, Peru.
Islas de Rosario, Colombia.
Isla Perro San Blas Islands, Panama.
Knip Beach, Curacao.
Maldives Islands.
Nassau, Bahamas.
Navagio Beach, Zakynthos, Greece.
Palawan, Philippines.
Peyto Lake, Alberta, Canada.
Plitvice Lakes, Croatia.
To Sua Ocean Trench, Samoa.
Trunk Bay, St. John, Virgin Islands.

Hawaii’s Favorite Blue Water Beaches

Hawaii is famous for its spectacular beaches; some of them have stunning colors. Most Hawaiian beaches feature white sand, but you will be surprised to know that some Hawaiian beaches have pink, green, red, and even black sand.

Here are some of Hawaii’s beautiful beaches where you can experience the most transparent blue waters.

Hanalei Bay, Kauai.
Kalapaki Beach, Kauai.
Kalihiwai Beach, Kauai.
Ko Olina Beach, Oahu.
Poipu Beach Park, Kauai.
Polihale State Park, Kauai.
Waimea Bay Beach Park, Oahu.
Waikiki Beach, Oahu. Waikiki.

Hawaii has one of the world’s best lifeguard systems; however, some remote Hawaiian beaches do not have lifeguard towers. It is recommended not to swim at a beach with no lifeguard.

Some Interesting Hawaiian Information

Hawaii’s nickname is the Aloha State.
Hawaii achieved statehood in 1959 as the 50^th US state.
Hawaii’s population is around 1,431,603 people.
Hawaii’s capital is Honolulu.
The biggest city in Hawaii is Honolulu.
Hawaii’s state bird is the Hawaiian goose.
Hawaii’s state flower is the yellow hibiscus.

Influences That can Alter Water’s Color

Let’s look at the different influences on ocean and water bodies other than the typical blue color we see in the water around Hawaii.

Turquoise

The turquoise color of the water in the Santa Barbara Channel is caused by a chalk-forming phytoplankton bloom called coccolithophores. This phytoplankton sheds calcium carbonate, which changes the color of the water when it interacts with it.

They typically bloom when the ocean waters are calm. However, the bloom has nothing to do with water temperatures.

When coccolithophores are abundant, they turn the ocean surface turquoise and are so clear they can even be seen via satellite. Coccolithophores are extremely important when they photosynthesize; they also absorb carbon in seawater and transform it into rigid plates called coccoliths made up of calcium carbonate like oyster shells.

This biological process constitutes one of the most crucial systems the Earth uses to change carbon into solid material, of which some end up on the ocean’s floor.

Bear Lake in Utah also has a turquoise appearance because of these abundant calcium carbonate floating microscopic particles.

Green

The Atlantic Ocean near the US east coast looks green due to the high density of algae in the water. Phytoplankton extracts electromagnetic radiation in the red and blue light spectrum and scatters the greens making the ocean look green.

Red

The Red Sea periodically experiences red blooms accredited to the high density of Trichodesmium erythraeum bacteria in the water, which turns the sea a red color upon dying.

Yellow

Decaying organic particles like peat and marine matter can make the ocean water look yellowish. Dissolved organic debris or sedimentary particles in high density can influence the color of any water body.

Brown

Runoffs from rivers and a high density of mud can influence the color of the water, making it brown. Rainwater which carries organic waste from forests into streams and rivers, flows into the sea, and the decomposed leaves and organic matter mix with the seawater, changing the color. Brown water is obvious when flooded muddy rivers flow into the ocean after a storm.

Black

Gray or black water is seen in a water body is usually an indication of plentiful growth of sulfur-oxidizing bacteria. Sulfur-oxidizing bacteria produce reactions the same as Iron Bacteria, causing blackening of the water or black slime.

The Haloclines

Borders between oceans are called Haloclines and are breathtaking. This is what is seen when the Pacific and Atlantic oceans meet. These Haloclines appear when the water in one ocean is around five times saltier than in the other ocean.

The Pacific and Atlantic oceans have different salinity levels, chemical compositions, and densities. The difference is noticeable from far.

Since these waters flow in opposite directions, they don’t mix. Perhaps in the future, they will gradually begin to merge.

There are also noticeable thermoclines between oceans with different temperatures, like the frigid water of the North Atlantic Ocean and the warm water of the Gulf Stream.

Conclusion

The water around Hawaii seems blue when sunlight hits the ocean because water absorbs red colors in the light spectrum first, and just like a filter, blue colors remain visible, making the water appear blue. The water may also seem green as light bounces off floating sediments and algae in the ocean.

Almost all sunlight that hits the ocean water is absorbed. Yellow, red, and green wavelengths are long and absorbed first; the shorter color wavelengths like blue remains and reflect, making the ocean seem blue.

Another reason the water around Hawaii is so blue and clear is due to the lack of murky sediment around its shoreline. Hawaii has heavier sediment that consists of volcanic rock, grainy sand, and coral skeletons that don’t get stirred up easily by waves and ocean currents.

Hawaii’s ocean water is clear and blue because of the absence of algae and organic materials that can affect the water’s color.

We hope we have answered your question about why Hawaii’s water is so blue. Whether participating in water activities or just watching the sunset from the beach, Hawaii’s iridescent blue water will enchant you.

Sources

Chrissie Smuts

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