For years, I have come across anemones which have such vibrant, red/pink tentacles. They are rare to see and every time I take a picture of them, the color looks drab. I try all different settings, even without strobe but it always looks so dull yet to the naked eye, it glows. What am I doing wrong? Below is an example of an unprocessed picture of an anemone that to the naked eye, was so vibrant.

Natural red light does not exist at a certain depth. What you see here is a derivative of green fluorescent protein (GFP), a red-fluorescent protein found inside the anemone. The protein generates the red light from green or blue light. (The fluorescence is excited by light with a very specific, shorter wavelength). If the flash is too strong, it will overpower the fluorescent light. Without flash it should work. No idea why it doesn’t in your case. I photographed a similar looking anemone some years ago without problems.

Dear Hiloboy,

dear all!

I was contacted by pm but would like to post my (extended) answer also here because I think it might be of interest for others es well, especially since my above answer might be unsatisfactory for some of you. To be honest: In fact, it somehow is.

Honestly, I don't think your photo looks bad. Mine looks very similar. I think our eyes are very easily fooled in this situation. They somehow "sense" that something unusual is going on, that there is light present in a color that shouldn't really exist under those conditions, or at least these colour does not exist anywhere near or around the red "glowing" object. There are probably other effects involved as well. Our visual system tends to perceive this red color as a very strong color accent.

Depending on the camera settings, the automatic white balance may also be working against the effect to some extent.

Sorry, but for the moment I don't have a better explanation either.

In fact, fluorescence underwater, or "fluo diving", is also very interesting from an ecological perspective. Why do fluorescent organisms occur mainly in shallow water? Because GFP acts as a natural sunscreen. The high-energy green and blue light is converted into lower-energy orange or red light. This reduces the risk that high-energy radiation will cause "sunburn" and thus damage or destroy tissue.

And now something a bit more off-topic regarding red light underwater:

For us photographers, it is often helpful to use red light as a focus light because it disturbs many underwater organisms less, especially fish. Why is that?

Because beyond a certain depth, red light no longer exists underwater. As a result, there has been little or no evolutionary selective pressure for the development of sensors (eyes) that can detect red light. After all, why would an organism "accidentally" evolve a sensor for a signal that simply does not exist in its natural environment? Most fish are unable to perceive red light, although there are notable exceptions. More on this in just a moment.

Still not enough crazy facts about red light underwater?

Some fish actually fluoresce red! They use this fluorescence to communicate with members of their own species, and their "language" cannot be eavesdropped on because other fish species cannot see it. It's like transmitting on a radio channel that no one else can monitor.

As always, exceptions prove the rule, because, of course, these particular fish species are able to perceive red light themselves!

And this is how it looks like when I increase the saturation (not selectively, this would be a lie) in Lightroom.

It does seem that the flash just overpowers what you might see in existing light. Try no flash, long exposure or higher ISO. Where does this anemone live?