The news came to light via an accidentally leaked press release, so details are still limited. But I do know that the Aqua will have a 6" E-ink screen with a resolution of 600 x 800. It has a touchscreen but no frontlight, and it's going to ship with 4GB Flash storage, Wifi. It will run Pocketbook's reading software with its broad support for a variety of ebook formats.
I don't have any details yet on the screen (and whether it too has been ruggedized), but early reports say that this ereader has a slightly modified design and is not just a regular model that has been dipped in a sealant. For one thing, the Aqua lacks a microSD card slot. This was sacrificed in order to reduce the number of weakpoints where water or dust might enter. The lack of a card slot will probably not be an issue for most readers - not unless you like to carry around a lot of PDFs.
With luck Pocketbook will also have seen fit to replace the standard 6" screen with one that is more impact resistant. Most ereaders ship with a E-ink screen built on a glass backplane, which as I'm sure you know is easy to damage. A few, like the Earl back country tablet, use a slightly more expensive E-ink screens based on a plastic or metal foil backplane. This makes the screen much more resistant to impact damage, and I am hoping that the Aqua will be equally rugged.
The Aqua is reportedly scheduled to ship in March 2014. There's no information yet on the price or availability, but Pocketbook has revealed that the Aqua will meet the IP57 standard for dust and water resistance. This means that you should be able to submerge the Aqua in up to a meter of water for 30 minutes, and should the Aqua come in the way of a high pressure stream of water, the ebook reader will continue to function.