Is iPhone 7 plus waterproof?

The iPhone 7 and iPhone 7 Plus are rated as being IP67 splash, water and dust resistant under IEC standard 60529. That means the iPhone 7 can survive being submerged in just over three feet of water for up to 30 minutes.

No, it does NOT mean it can survive being submerged at any depth for any length of time.

Those statistics refer to laboratory testing under controlled conditions.

It may survive being submerged. Then again, it may not.

The warranty does not cover liquid damage and a liquid damaged phone can not be repaired.