The patent came to light this week but was filed back in July 2014. It focuses on a rubber port cover that loses and regains its shape - so it would allow a headphone jack to be plugged in but then seal the gap again once the headphones were removed, for example.
Ports are one of the weak links when it comes to making a phone that's waterproof - how do you stop water getting into the handset when Lightning cables and other peripherals need to be inserted?
All of those hints could mean we'll see a fully waterproof iPhone 7, though don't bet your house on it for the time being. It's worth noting too that the patent has yet to be granted to Apple.
Ideas floated in industry patents don't always end up seeing the light of day but they can be very useful in predicting which way a manufacturer is thinking - and it seems Apple is thinking long and hard about how to add waterproofing to its flagship phones.