Cleaning the MK2

Thats salt crystals that have accumilated with each dive, theyre v destructive, You need to scrub the surface with a soft brush using v  light soap detergent then rinse it thouroughly in fresh water after, it may take a few goes before its all clean, make sure that water you use it distilled if you live in an area with hard water!

If you use the watch during showers, this happens too, is soap residue, I used to clean mine with and old toothbrush and dry with paper towel. Nowadays I don't take a shower wearing the watch.

Looks more like soap residue or calcium than salt crystals. Could be from hard water.

Sun cream also leaves similar residue.

Thanks everyone for the response. I followed the instructions and cleaned with a soft toothbrush using a light dishwasher liquid... using tap water for now.

The watch now looks like new, I won't use it to shower anymore, will continue to soak it in fresh water after diving (most of the times there isn't distilled water on hand)

Keep in mind that a build up of soap and other residue has potential to affect sensors such as pressure located between start/stop and back/lap buttons.

Best to keep soap away from these altogether and remove the watch during a shower.

About once a month I'll add a few cups of vinegar to my rinse bin and let regs and electronics soak for 20 or so minutes. It's a gentle cleaner that'll keep calcium and salt buildup down, especially if you have hard water. Then I'll use a towel to pat stuff down. 

If you use anything acidic, like vinegar, you should rinse it in clean water after it, then use a towel or else.

Leaving non PH neutral on the stuff is not the best in long run.

I had other suck issues, use soap and a soft toothbrush to clean it all up. 

Nunca te duches con el reloj. El agua caliente rompe las juntas.

Mientras te duchas pon el reloj en agua dulce dentro de un recipiente y muévelo sin golpear las paredes del recipiente.

Hago lo mismo después de cada entreno .. correr bicicleta, etc.

Así lo hago yo.        

Never shower with the watch. Hot water breaks the joints.

While showering, put the watch in fresh water in a container and move it without hitting the walls of the container.

I do the same after every workout .. bike riding, etc.

So i do