Seakayaking puts a waterproof case to the ultimate test. Cases that never leaked using them while hiking or on the bike (and even on the motorbike - speeding down the German Highways in non-stop rain on "naked bike" is an exposed session for a map case) don't guarantee the needed protection to the elements on the deck of the seakayak or in the pocket of the PFD.
Another proven system is the Zölzer-system - shown above is the recent edition where you don't need to disassemble the complete rail to open the case: you can slide the case in and out. I do prefer however the simple old system, where the rails is bolted through the fabric of the case. This takes more work to open and close the bag - but the edges of the case in the new system are (to) fragile for the sliding operation. Although the new case was always used with care: within a year the edges split up. The old case of Zölzer is more robust: the edges of the case are still intact after 8 years of intensive use. Minor points of the Zölzer-design are the unwieldy character of the aluminium rail and the little pieces - I have dropped several screws in the water...
The best waterproof case? Home made cases like Elko, Axel, Paul and Reinout make... So satisfying that "Do it yourself " performs better than money can buy! ;-)