Underwater White Balance

If you're new to underwater photography, one thing you'll quickly realize is that all of your pictures come out blue. If you want to know why, read my article on colors underwater.

Now that you know why, you want to know what you can do about it. Before you bought your camera, you looked at magazines and online photo galleries. None of those pictures have that blue haze.

To remedy this problem, you basically have two options: a strobe (flash) and adjusting white balance.

Underwater strobe / flash

Underwater strobe
Water (more specifically, stuff in water) absorbs frequencies of light the farther the light travels. Very quickly then, red light is absorbed, leaving everything a blue tint. One option is to then reintroduce white light, which contains all frequencies, into the environment.

If you're taking a picture of a piece of coral at 10 meters, the light seen by your camera reflected off the coral has traveled over 10 meters, and will thus be dominantly blue, even if the camera is less than 1 meter away from the coral. By using a strobe, the camera will see not only the light that has traveled 10 meters, but the white light from the flash, which reintroduced the missing reds.

There are two downsides, however. First, the most common flash is the camera's built-in flash. While fine for taking pictures of friends on land, underwater it tends to produce backscatter, where the light reflects off of particles in the water. The only way to prevent this with a built-in flash is to only use it up close (less than a meter).

Even if you manage to avoid backscatter, on-camera flash tends to be a bit harsh, giving you a fish equivalent of that "deer in headlights" look. An alternative is an external strobe which is attached by an adjustable arm. This lets you control the lighting more finely, both by arranging the direction (via the arm) and the strength to get a perfect exposure.

External strobes are expensive, but the vast majority of professional underwater photos you see used them. In the future we will look at them in more detail (as I learn more about them).

White balance

Canon Powershot SD1100 IS
The other option available is by adjusting your camera's white balance. You can adjust white balance two ways: on your camera and on your computer. However, you can only really adjust it on your computer if the picture was taken in an appropriate format (like RAW). This doesn't apply for most point-and-shoot cameras. If you want to learn how to "cheat" white balancing on a computer, read my article on color balancing underwater pictures.

Most point-and-shoot cameras do support manual white balance, though. Check your camera's documentation, but the process usually goes like this:

  1. Set to manual white balance. Enter your camera's system menus. You will probably find some settings for taking pictures indoors, on a sunny day, at night, etc. You are looking for anything that says "white balance" or maybe even "AWB" (automatic white balance). When you find it, you will want to change to manual.
  2. Change the white balance. While still in the menu, you need to set the white balance. Point your camera at something you know is white and "take" a picture or press the appropriate button. The camera will record your settings.
  3. Take your pictures. You can now take pictures as usual. Because light is absorbed differently at different depths, a white balance setting is only appropriate for around the depth it was set at. If you go deeper or shallower, you will need to repeat step 2.

Below I have side-by-side photos of the same coral with and without manual white balance.
White balance before / after
The difference should be clear. Notice also how the after picture still isn't quite perfect. While it's much better, you may want to still touch up your pictures on the computer later.

What is white balance?

Cameras just record what they see, which is a bunch of colors (light). These colors are the result of some light source and how that light is absorbed and reflected. Above water, light is not usually absorbed significantly, but light source colors can vary. For instance, indoor fluorescent lighting can be a harsh white, or some lights can be orangey.

To account for this, cameras allow you to change the white balance. This redefines what the camera thinks of as white by allowing you to intervene with your knowledge. If you know a wall is white, but it appears yellow because of the room's lighting, you can point your camera at it and "tell" it that "this is white". The camera will then shift internally to account for this. If the camera were a person, it would say, "Aah, this wall looks yellow, but is actually white (my owner told me so). This means everything in the room is going to look a little yellow. I will compensate for this by removing yellows."

Underwater, we are doing the same thing, except instead of compensating for off-colored light, we are adjusting for red light frequencies being absorbed. When we tell the camera that something is white that looks blue, the camera adjusts by removing blues.

I hope this helps your understanding of white balance. The best way to understand it is to play around with it. Get out your camera manual and play, even above water. If you don't have your manual, look for it online at your camera manufacturer's website. Try silly things, like pointing to a blue wall and setting manual white balance. What does is do to your pictures? Think about what it will do first, then try it and see if you were right.

How Many Divers Are There?

It's a simple question: how many certified scuba divers are actually out there? Unfortunately the answer is not so simple, for several reasons.


  • Organizations don't share data. Certification agencies tend to not release data about how many divers they certify. One exception is PADI, although they have been accused of inflating their numbers in the past. Without reliable numbers, it's much harder to get a good estimate.
  • Lack of trends. For the few years that data is available, we can't extract any meaningful trends. For instance, we can't say anything as strong as "for 20 years diver certification has grown …

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Physical description

Grouper have oblong, stout bodies and a large mouth, probably not unlike some of your relatives. Typical lengths are over a meter, and can get to over 2 meters for the various giant varieties.

Their large mouths resemble a frown, contributing to the grouper's unfriendly appearance. If you catch one with its mouth open, you will get a glimpse …

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The first place I ever dove after certification was Bermuda. On one boat dive we were briefed by the divemaster in preparation for our first dive. He asked if there were any questions.

"Yeah, should we make a safety stop", I asked. Fresh out of my checkout dives, I couldn't remember the rules for when to make a safety stop.

The divemaster scoffed at me. "We'll hardly be going deep enough to require a safety stop."

Safety Stop
Fast forward a few years. I've read a mountain of material for fun and as part of my professional development. Looking back on this …

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A year ago I was working in New Zealand. I was interested in what the local diving had to offer, so I signed up for a small trip off the local coast of Wellington. What happened on that trip turned out to be a valuable learning experience.

It was a cold morning when we pushed off from shore in a small fishing boat, six divers and two crew. I was a little nervous since I knew the water would be cold---it was winter there, after all. I wore an old, uncomfortable rented wetsuit. A farmer john that had seen more …

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