Is the iPhone 5S waterproof

no!

it is not waterproof, if you want a waterproof case, LifeProof makes pretty good ones

I second that, the LifeProofs are the max.

Don't confuse waterproof with water resistant. LifeProof guarantees a dry phone up to 6 feet underwater for 60 minutes. Griffin Survivor Extreme only guarantees dryness if splashed and then shaken dry, never under submersion.