Can a rusty Micro SD card be fixed? Or have I lost all of my diving photos?

I think it's dead but you may try asking at a computer repair shop that offers data recovery.

It isn't rust as there are no ferrous metals in a SD card. It is corrosion from interaction of the differing materials in the the card. Electronic circuits use various metals, and when two dissimilar metals that are in contact with each other are immersed into salt-water, a corrosive galvanic current is generated, which actually dissolves the less noble metal. In as little as 5 minutes of immersion, some of the metals will begin to dissolve. If left in salt water long enough, the metals in the internal components; circuit traces, etc. will actually dissolve. But even before the metal is completely eaten through, the circuit can fail. I once took a camera swimming in salt water (no the camera was not waterproof), and my son did it once as well. In both cases, we were able to recover the card's contents. A micro card will be a bit more difficult as it is smaller. But don't use WD40, thinner, or anything like that. You will just make it worse, and if you then stick the card in your computer, you will introduce those liquids into your computer and mess it up too. This is a last resort effort. First, find an abrasive pencil - like those used for correcting typewriter mistakes - if you can even find such a thing. What you want to do is to lightly rough up the surface of the contacts on the card. Since you are going to throw the card away anyway, you are not so much caring if you scratch the metal contacts. If you scratch the metal contacts, that is good. If you can get shiny metal to show, your chances are improving. Then blow off any metal flakes or anything else that comes off the contacts (you don't want those in your computer), and try to read the card. If that doesn't fix it, there might be some corrosion in the card internally. If that is the case, you might have a problem in reading the card. If you just got the card wet, you might have been able to run it under a sink with clean fresh water to purge any salt water in the card's innards. The only option - other than taking it to a shop (but there are not many shops specializing in this kind of thing) - is to open the card and try to remove some of the corrosion. But if you don't know what you are doing you will probably ruin it anyway. All of these things are last-resort efforts anyway. http://www.althephoto.com/tips/wetcamera.php Best of luck.

You can clean the rust off. I would use WD40 since it won't hurt the plastic like thinner would.

You need a company that really knows what they are doing, MicroSD cards are tiny and they have serious internal components, they can crack, fall apart and stop functioning altogether for various reasons. Best idea is to use a service that has been around a while, we used http://www.eProvided.com with great success. There are many other companies out there but so many of them are mom and pop. It is possible to have special adapters to connect into the test points on these little cards but for proper data recovery you need a specialist who knows what to do. A video I found that shows a bit of the things data recovery companies can manage: http://www.youtube.com/watch?v=W0P5F_TvBBs

Sure you can try fixing the SD card yourself, but it could (though may not) make matters worse. Your best bet is to call the card manufacturer first and see what they recommend. They can help assess whether or not your card can be fixed, or if it's worth using a specialist. Since your card is damaged, not corrupted, there is usually an extra charge for trying to recover images from physically damaged media. The card manufacturer may offer recovery services. If not, a company such a LT technology offers the service: http://lc-tech.com/services/recoveryservices.html

1. Wash the memory card off in tap water and dry. 2. Use a pink pearl eraser (the abrasive pink erasers on the end of a yellow pencil work great) and rub the contacts until they shine. You are trying to remove the corrosion byproducts caused by electrolytic corrosion. 3. Wipe off all the eraser grit with a clean cloth and brush (toothbrush works fine). If you have compressed air, give it a good blow to remove grit. 4. See if you can read the contents of the card. If not, the internals of the memory card are damaged and you probably can't retrieve the images unless you spend a lot of money. 5. Throw the memory card in the rubbish. You may want to smash it with a hammer so others can't view your images.