Alongside its gorgeous, rounded 5.7-inch screen and iris scanner, the other Samsung Galaxy Note 7 feature that is capturing plenty of attention since its official launch is its waterproofing.

Indeed, Samsung had set up an enormous tank of water at the London leg of its Unpacked unveiling, just to show how effective the phone is when submerged. The S Pen too.

We have to say it's very impressive. It's not the first phone with IP68 water and dust proofing - the Sony Xperia Z5 and Samsung's own Galaxy S7 and S7 edge handsets are similarly rated, for example - but it's the first time we've seen a stylus working with a normal consumer device under water.

But what does the IP68 rating actually mean in real terms? And does it mean the phone will survive a dunking in the toilet? Here is our short and handy guide.

Pocket-lintSamsung Galaxy Note 7 wet-5

An Ingress Protection (IP) rating is awarded to a device to give a simple, clear indication of how protected it is from foreign bodies, whether that be moisture of some kind or dust.

The first number signifies, on a scale up to seven, how protected the device is from intrusion. The second, on a scale up to nine, gives an indication of how protected it is from moisture.

The number "6" means that a device is "protected against dust that may harm equipment", while the second number, "8", means that it is also protected against temporary immersion in water.

The Note 7 therefore, with its IP68 rating, is rated as "dust tight" and can be immersed in water for a prolonged but not indefinite period of time.

During the launch keynote it was joked that you can even drop the Note 7 down a toilet and it will survive. We haven't tried it yet, but there's no reason to think that's not true.

Samsung claims that the Note 7 can be submerged under water down to a depth of around 1.5 metres (5 feet) for 30 minutes, which is impressive.

More impressive still is that it remains water resistant even when the S Pen is removed from the handset. The hole where it usually slots in is also protected.

The S Pen too is IP68 rated, so can also be submerged under water.

So it's very likely the phone with survive a drop into a loo, although we wouldn't recommend it as the case isn't rugged and it might be physically damaged in the fall.

Pocket-lintSamsung Galaxy Note 7 wet-3

Thanks to the "6" in the IP68 rating, the phone is also resistant to sand, so is far better suited to take along on a beach holiday than many handsets.

However, just because something is resistant to some of the elements doesn't mean you should purposely expose it to them. Drop the phone on a pebble, for example, and you could have an issue.

We'd still advise you protect it further in a decent case.

The Samsung Galaxy Note 7 will be available for pre-order from 16 August and will ship from 2 September.