Why your photos look blue under water
Everyone notices it on the first dive: what your eyes saw as a colourful reef comes back from the camera as a flat blue wall. The reason is not your camera, and understanding it is what stops you from overcorrecting later.
Water is a colour filter you cannot switch off
Light travels to your subject and back to the lens through water, and water absorbs wavelengths at very different rates. Long wavelengths go first, short wavelengths survive longest. That is the whole story, and everything else follows from it.
- 0 mFull spectrum intact
- 5 mRed is already fading badly
- 10 mOrange going, yellow weakening
- 20 mYellow mostly gone
- 30 mBlue and green only
The number that actually matters is not depth. It is the total distance the light travels: down to your subject and back to your lens. A subject 4 metres away on a 6-metre dive can lose more colour than a subject 30 cm away on a 25-metre dive.
Why your eyes lied to you
You remember more colour than the camera recorded, and you are not imagining it. Your visual system adapts continuously: it rebalances what it receives against context and expectation, so a brain that knows a sponge is red will keep reading it as reddish long after the light says otherwise.
A sensor has no such context. It records what arrives and nothing else. The gap between the two is exactly the gap you are closing when you edit.
The four things that decide how blue your photo is
| Factor | Effect |
|---|---|
| Distance to subject | The single biggest factor. Halving the distance does more for colour than any edit. |
| Depth | Sets how much colour is left in the ambient light to begin with. |
| Artificial light | A strobe or video light restores the full spectrum, but only within its short effective range. |
| Water clarity | Suspended particles scatter light, cutting contrast and adding a veil on top of the colour loss. |
Why a red filter is not the same as editing
A red filter physically blocks part of the blue and green light before it reaches the sensor, which rebalances the channels in-camera. It works, with two caveats: it costs you roughly a stop or two of light, and it becomes useless the moment you switch on a strobe, because the strobe already provides full-spectrum light.
Editing does the rebalancing afterwards instead. Neither can invent information that was never recorded. If red reached the sensor as pure noise, no filter and no slider will turn that noise into detail.
What this means for how you edit
Once you understand that the blue cast is wavelength absorption and not a camera fault, two things follow.
First, the correction has to scale with the photo. A photo that lost a little red needs a little red back. Applying a fixed correction to every image is what produces violet water and pink divers, because you are adding red that was never missing.
Second, the blue is not the enemy. It is part of the scene, and removing it entirely leaves you with a grey, lifeless image that looks nothing like being under water. The goal is to restore what was lost, not to neutralise what is there.
See it on your own photo
The editor measures each image and calculates the correction it actually needs, instead of applying fixed values. Free, no watermark, no sign-up, and nothing is uploaded: everything runs in your browser.
Open the editorFrequently asked questions
At what depth does red disappear?
Red starts weakening almost immediately and is largely gone by about 5 metres, followed by orange and then yellow. By 30 metres the ambient light is essentially blue and green.
Does a more expensive camera fix this?
No. The absorption happens in the water, before the light reaches any sensor. A better camera records the remaining signal more cleanly, which gives you more room when editing, but it cannot record light that never arrived.
Is it better to use a red filter or to edit afterwards?
For ambient-light wide angle at moderate depth, a filter helps. With a strobe it is counterproductive. Editing is more flexible and costs no light, which is why most people shooting RAW correct afterwards.
Why does my photo turn purple when I correct it?
Because you added more red than was missing. It usually happens when a fixed correction is applied to a photo that already had plenty of red. Lower the intensity.
Keep reading
Now that you know why it happens, the practical side is in how to properly edit a diving photo and in the step-by-step colour recovery guide. If you are choosing a tool, here is the comparison.