Why is my dive video blue?
Not because your camera is bad. Water is a colour filter, and it gets stronger with every metre. Once you see how, the fix is obvious.
Water eats light, one colour at a time
Sunlight contains every colour. Water absorbs the long wavelengths first: red is mostly gone by five metres, orange by ten, yellow by twenty. Green survives longest after blue. That is why a diver's red fin turns brown, then black, while the water stays blue.
| Depth | What is left | What you see |
|---|---|---|
| 0–5 m | Everything, red fading | Slight cyan cast, snorkelling look |
| 5–10 m | No red | Skin goes grey, corals lose warmth |
| 10–20 m | No red, no orange | Everything blue-green, "GoPro blue" |
| 20–30 m | Blue and some green | Monochrome blue, only a torch shows colour |
Distance counts twice. Light travels down to the subject and then sideways to your lens, so a reef three metres away at ten metres depth has lost as much red as a reef right in front of you at thirteen metres.
Why the camera cannot fix it
Automatic white balance looks at the whole frame and tries to make the average neutral. Underwater the average is blue, so it pushes red – but it can only amplify what was recorded, and at fifteen metres the red channel is mostly noise. Pushing noise makes grain, not colour.
Why a red filter only half works
A filter removes blue so the sensor's channels are closer to balanced before the picture is taken. That genuinely helps at the depth the filter was designed for. Above it the picture turns magenta, below it the filter cannot invent red that is not there. Red filter vs software goes into the details.
What per-frame correction does
- Measures the average red, green and blue of the frame and estimates how much red the water removed.
- Adds back red per pixel in proportion to what each pixel should have had, with a cap so highlights and sunbeams stay white.
- Balances the channels and stretches the contrast the water flattened, with temporal smoothing so a video never flickers.
- Adapts the strength to the scene: open water needs a gentle hand, a reef can take the full correction, hazy snorkelling water needs a cap on saturation.
That is exactly what the free browser tool does, on your own graphics card, in about the time it takes to play the clip.
Frequently asked
Does a deeper dive always mean a bluer video?
Yes, and so does more distance between the lens and the subject. Shooting close is the single best thing you can do for colour.
Can colour that was never recorded be recovered?
Partly. The red channel is weak, not absent, down to about 20 metres. Correction amplifies and rebalances it; beyond that, a torch or video light is the only way to get real red.
Why do my night dive videos look fine?
Your torch provides full-spectrum light at short distance, so the water has no chance to absorb it. The tool detects this and only balances gently.