This seems to be the idea behind the Waterbuoy. It’s a keychain with a rubber ballon that automatically inflates shortly after hitting the water; it also has a LED beacon that can be seen from a large distance (250m at night). So, in case you happen to be on Titanic 2, you can hang your valuables from this (it holds up to 1 kg) and know that, in case you survive, you’ll be able to find them.

So, get one if you’re sailing and paranoid or unsure of the safety of the journey. Or if you’ve got $30 lying around and you want to make sure your stuff will float in case you drop them in the pool.

How much under $29.99?
Exactly $29.80 on Firebox.com.

Via Coolest Gadgets