It has already been documented that water-resistance does not mean waterproof. And also, that the depth of the water rating (in terms of meters) will signify if you can submerge it for any period.
Past being knowledgeable and understanding of the water-rating, there are individual bodies of water that you should avoid altogether. One that comes to mind is salt water. Indeed, salt water will corrode metal five times faster than regular water would. But, still, a metal such as stainless steel can hold up reasonably well in salt water.
But, one body of water you may not think of is a pool. It all has to do with the chlorine injected into the pool. This, much like salt in the ocean, can cause corrosion to the metal.