Player is drowning underwater (CREATIVE)

I can confirm for 0.10.4 on iPhone 6 plus (iOS 8.1.3). Explanation: drowning particles appear after approximately 15 seconds when underwater in creative mode. This correlates with the time needed to deplete the oxygen bar in survival mode, suggesting that, unlike health, the player in creative does not have unlimited oxygen.

That thing is normal.

The drowning effect does not appear to be intended, see MC-2145.
However, this issue has already been reported as MCPE-5509

Players in creative mode do not take damage, if that is a bug, the player in creative mode is taking damage.