Tag Archives: Scuba

Light and Color Below the Surface

Have you ever gone diving and noticed that colors above the surface may look very different than colors below? This is because light and color are very different underwater. Water is very good at absorbing light, and to understand this a little bit better, let’s talk about good ol’ Roy G. Biv.


(Light on the surface appears very different than light below.)

Roy G. Biv (an acronym for the color spectrum) stands for the colors red, orange, yellow, green, blue, indigo, and violet. These colors are in order from lowest to highest energy. Sunlight contains all of the colors of our visible color spectrum and these colors combined together create white light. As you travel from the surface to deeper waters, the amount of light changes and decreases with depth.

light wave

(Red light has the longest wavelength as shown above.)

Red light has the longest wavelength and therefore has the least amount of energy in the color spectrum. Wavelength decreases as energy increases as you move from red to violet light across the color spectrum. Blue light however penetrates the water the best. This is why the ocean can appear in many different shades of blue. Unlike blue light, red light becomes quickly filtered from water as the depth increases. At around 300 feet, no visible light can penetrate the water at all!

Let’s take an apple for example. At the surface an apple appears red. It appears red because it is reflecting that red light from the sun. When taking this apple down to depth at around 70 feet however, it lacks the red coloration and appears greyish. This is because the deeper you go, there is less and less red light to reflect off the apple. This is an amazing adaptation for deep-sea creatures to have. Deep-sea creatures that are red will appear less visible to prey.

light brooke

(Left: Apple appears brownish at depth.)










Written By: Brooke Fox

Equalize Early and Often

Have you ever wanted to dive below the surface of the water? If so, it’s important to learn more about equalizing. As you descend, pressure builds up in the inner and outer parts of your ears, which at a few feet can be uncomfortable, but a bit deeper, can lead to major ear damage. Equalizing balances out that pressure, and opens something called the Eustachian tubes, which connect to the empty air space of the middle ear. Throughout our daily lives, we are often equalizing the pressure in our ears by simply swallowing or yawning. When we dive underwater however, we often need a more deliberate method to make sure that the pressure becomes equalized.

IMG_4356One of the most common techniques for equalizing underwater is something called the Valsalva maneuver. For this method, you simply pinch your nose, keep your mouth closed, and blow out. The high amount of pressure in your throat then prompts the Eustachian tubes to open and equalize the pressure in your ears. This method is one of the first that is generally taught to new divers, but it is important to understand that there are still risks. Making sure not to blow too hard can help to prevent damage to the round and oval windows in the inner ear. Other common equalizing techniques include the Toynbee Method, the Lowry Technique, and Voluntary Tubal Opening, among others. For the Toynbee Method, the nose is pinched, and the diver swallows to open the Eustachian tubes. The Lowry Technique combines both the Valsalva and Toynbee methods by pinching the nose and then blowing out and swallowing at the same time. As divers practice equalizing, they may become more comfortable with a specific technique, or learn to control their muscles especially well. For Voluntary Tubal Opening, a diver may learn how to continuously equalize the pressure in their ears by tensing their throat and jutting their lower jaw forward and down similar to a yawn.

So when do you equalize? The most important things to remember are to equalize early and to equalize often. If you have a dive planned for later in the day, it is a good idea to start equalizing a few hours beforehand every few minutes. Before going underwater, always equalize on the surface. Then, as you descend, make an effort to equalize about every two feet to avoid the tearing of tissue or eardrum damage. If at any point your ears hurt, make sure you don’t push through the pain and continue to descend. Equalization takes practice, but diving underwater can take you to a whole new world in the ocean!

Written by: Jaclyn Lucas


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