Troubleshooting
Dive Computer Screen Fogging: Condensation or a Leak?
You look down mid-dive, or just after surfacing, and the screen of your dive computer has a fine mist across it. Sometimes it clears on its own within minutes. Sometimes there are visible droplets that don't go away. Those two situations can mean very different things.
This guide explains the difference between fog on the outside, condensation inside and actual water ingress, how to check which one you're dealing with, and when the right answer is to stop diving the computer and contact the manufacturer.
Quick answer
- Fog on the outside of the lens is common and harmless. Wipe it or use a screen protector that resists it.
- A faint mist inside that clears quickly as the temperature evens out can be condensation of humidity trapped at assembly or a battery change.
- Visible droplets, salt crust or corrosion inside the case suggest a leak. Stop diving it and contact the manufacturer or service center.
- Battery hatches and user-serviced seals are the most common entry points on replaceable-battery models.
- Don't try to heat or open a sealed computer to dry it. You can make a small problem permanent.
Outside fog, inside condensation or a leak
The first job is figuring out which surface the moisture is on. It sounds obvious, but in a hurry on a boat it's easy to misjudge.
| What you see | Most likely | What to do |
|---|---|---|
| Mist you can wipe off with a finger | Outside fog | Wipe, rinse, consider a screen protector |
| Fine haze under the lens that clears as the unit warms or cools to room temperature | Internal condensation from trapped humidity | Monitor closely; contact the manufacturer if it recurs |
| Haze appearing after a battery change | Humid air sealed in during the change, or a seal not seated | Check the hatch and O-ring per your manual; contact service if unsure |
| Droplets, beads or pooled water | Water ingress | Stop diving it; contact manufacturer or service |
| White crust, green or brown marks inside | Salt and corrosion from a past leak | Stop diving it; service or replace |
| Erratic display, buttons acting up, sudden battery drain | Possible electronic damage from water | Stop diving it; contact manufacturer |
Why condensation forms inside a sealed case
Air always holds some water vapor. If a computer is sealed in a warm, humid place, such as a tropical dive deck or a bathroom, that humid air is trapped inside. When you jump into cooler water, the lens cools quickly and the trapped vapor can condense on the inside of it, just like a cold drink fogging on a hot day.
A small, temporary haze from this effect may clear as the temperature evens out. The difference from a leak is that no new water is coming in. The amount of moisture is fixed, it's small, and it moves back into the air as the temperatures equalize.
That said, a computer that repeatedly fogs inside is telling you something. Either humid air is getting in somewhere, or a seal isn't as tight as it should be. Repeated internal fogging is worth a call to the manufacturer even if the computer otherwise works.
Where water gets in
Battery hatch
On user-replaceable designs, a hair, grain of sand or twisted O-ring under the hatch is the classic cause of a leak.
Buttons
Mechanical push buttons have seals that can wear over many years and many presses.
Lens bond
A hard knock can crack or loosen the lens or its seal, sometimes without obvious damage.
Sensor area
Impact or corrosion around the pressure sensor housing can compromise the seal there.
Factory-sealed rechargeable computers remove the battery hatch as a leak point, which is one of the arguments for that design. Our comparison of user-serviceable vs factory-sealed battery designs covers the full trade-off.
What to do the moment you notice it
- Finish the dive safely. If the computer is still working and readable, follow your normal procedures. If it fails or becomes unreadable, follow your training for a computer failure, which usually means ending the dive with your buddy according to the plan your agency taught you.
- On the surface, check which side the moisture is on. Wipe the lens dry and look again in good light.
- Rinse in fresh water as you normally would, then dry the outside with a soft cloth.
- Don't open it on the boat unless your manual describes a user procedure and you're somewhere clean and dry. Opening a hatch in salt spray and sand can make things worse.
- Watch it at room temperature. If a light haze clears and never returns, note it. If droplets remain or the haze keeps coming back, stop diving it.
- Contact the manufacturer or an authorized service center. Describe what you saw, when it started, and any recent battery change or knocks. Photos help.
What not to do
- Don't put it in a hot car, on a heater or in an oven. High heat can damage seals, the battery and the display.
- Don't use a hair dryer on high heat to try to evaporate internal moisture.
- Don't pry the lens or case open on a sealed unit. It voids warranties and damages seals.
- Don't keep diving it "to see what happens". Water inside electronics tends to get worse, not better.
- Don't rely on a bag of rice as a fix. It may help absorb surface moisture outside, but it won't reliably dry a sealed case and it adds dust.
Preventing it in the first place
Battery changes
If your computer has a user-replaceable battery, the battery change is the riskiest moment for its seals. Do it in a cool, dry, clean room, not on a humid deck. Inspect the O-ring, keep it free of hair and grit, use only the lubricant your manual specifies, and seat the hatch exactly as described. Many divers prefer to have a dealer change the battery and pressure test the unit, especially before a big trip.
Browse battery replacement kits
Storage
Store the computer clean, dry and out of direct sun in a cool, low-humidity spot. A padded case keeps it from getting knocked around in a gear bag, and a small sachet of silica gel in your storage box can help keep the air around it dry.
Shop protective cases Shop reusable silica gel packs
Impacts
Lenses take a lot of abuse from boat ladders, rocks and tank valves. A screen protector won't stop a hard impact from stressing a seal, but it reduces scratches and lets you see cracks more clearly. Our guide to screen protectors covers film vs glass.
Temperature shocks
Leaving a computer in a scorching hot car or in full tropical sun and then jumping into cool water maximizes the temperature swing. Keep it shaded between dives.
Warranty and service questions to ask
- Is water ingress covered under the warranty, and does it depend on who changed the battery?
- Does the service center pressure test after a battery change or seal service?
- Will they recover your dive log before repairs, if that matters to you?
- How long is the turnaround, and do they offer a loaner or replacement program?
Our guide to dive gear warranties explains common exclusions to look for.
FAQ
Is fog inside my dive computer always a leak?
Not always. A light haze that clears as the temperature evens out can be condensation from humid air trapped inside. Droplets, crust or recurring fog suggest a leak and need inspection.
Can I keep diving if the fog clears?
If it was a one-off light haze that cleared fully and the computer works normally, many divers monitor it closely. If it returns or you see droplets, stop diving it and contact the manufacturer.
Does a rechargeable computer avoid leaks?
Sealed rechargeable designs remove the battery hatch as a leak point, but lenses, buttons and other seals can still fail, usually after impacts or long use.
Should I dry my computer with heat?
No. High heat can damage seals, batteries and displays. Contact the manufacturer for advice instead.
The bottom line
Fog on the outside is a nuisance. A brief inside haze that clears may be trapped humidity. Droplets, crust or fog that keeps coming back mean the seal has failed, and the computer needs inspection before you dive it again. Be careful with battery changes, store it dry and shaded, and have a backup plan for trips. When your computer is out of action, follow your training agency's guidance and dive within your certification with a working instrument.