Your electronics probably weren't made for underwater exploration, but that doesn't mean you're out of luck. Here are a few unusual options for waterproofing your gear, plus one mind-blowing commercial option.
Use A Condom
Not just any condom, but a very clear, un-lubricated condom. With a desiccant bag to absorb humidity and some wetsuit glue, you've got a cheap, homemade underwater housing for all sorts of gear. This works great for your point and shoot digital camera, but can work well with mobile phones and remote controls too.
Put it in a Bottle
If you don't need to actually use your gadget but still want some simple waterproofing, a thermos or wide-mouthed water bottle may do the trick. If they can keep liquids in, most of the time they can keep liquids out.
If you're taking electronics underwater, you'll probably need a means of powering them. Waterproofing batteries is actually very quick and easy with urethane waterproof coating. Just paint a little around the top seal of the battery and you're done. Check out the complete guide at Instructables.
If you need to waterproof anything but keep it usable, Golden Shellback's waterproof coating is marketed as "splash proof" but claims to actually waterproof many electronics while retaining their full functionality. It sounds crazy, but after seeing a demo in person, Gizmodo was convinced.
Have any waterproofing suggestions of your own? Post them in the comments!