This is very easy to obtain and you have a few options on how to go about it. You will need to be in survival mode to get this, creative will NOT
If you have the resources (9 gold blocks and an apple), just craft a golden apple, eat it, then go jump into some water. Make sure you're completely submerged! The effects of the golden apple will cause you to lose no health and two minutes later you will have your achievement.
Alternatively you can create a Potion of Water Breathing (nether wart and puffer fish) which will also keep you alive long enough to net this achievement.Another alternative:
Use the Notch Apple world found below to instantly have ready-to-eat apples! Be sure to thank member Itzz Sh0wt1m3
for creating the world! Achievement worlds
That's it! Good luck and please comment with any improvements I could make.