iOS 10 has added the ability to check whether there's water in the Lightning port.
See also: How to undo iOS 10's most annoying feature
If you're unlucky enough to get water in the Lightning port, iOS 10 throws up this handy message:
Be aware though that this feature only seems to be present on the 6s, 6s Plus, and SE.
You might be wondering how I got this message up. Simple. I just licked the Lightning connector before inserting into the port. No rocket science involved, and there was no lasting damage to my iPhone.
However, my uncalibrated testing suggests that you don't need a lot of water in the Lightning port to cause the message to appear.
Is this feature a precursor to a water-resistant iPhone? While only time will tell for sure, having the ability to detect if there's water present in the Lightning port would be a handy feature for a water-resistant phone, since the presence of any water could cause a damaging short-circuit.