ThirdCrank wrote (on another thread - http://forum.ctc.org.uk/viewtopic.php?f=16&t=24835&hilit=ortlieb#p196680)
On the other hand, an Ortleib roll-top properly fastened could be completely submerged and remain waterproof.
Having just taken delivery of some new Ortlieb panniers - how do you close them properly? I am baffled - the instructions look like a dish of spaghetti with lines and arrows everywhere. I am feeling particularly inept at the moment... (They had no carradice due in stock til mid-July - I was impatient!)