The Aqua Jewel is one of my favorite items that drop from the Pandarian champions. The item increases swim speed by 50% and allows underwater breathing for 10 minutes. It has a one hour cooldown.
The Aqua Jewel is a rare drop from the Pandarian champion Sahn Tidehunter. Sahn can be found in Vale of Eternal Blossoms (approximate coordinates 62,55).
The coolest thing about this item though is that for 10 minutes you appear to have this blue translucent watery look that you can see right through! A few in my group have this item and we use it all the time especially in PVP when we are trying to hide out.
When you mount up whatever your riding also becomes translucent. So below are a bunch of screenshots of me on different mounts. Can you identify them all?