Bought this to put my sons rollmat in when doing his practice Duke of Edinburgh walk. The bag is roomy and the toggle closes up to cover the whole mat. Wasn't sure how waterproof it would be, however after four days walking one day in torrential rain and strong winds (tail end of a tropical storm and quite extreme conditions) the rollmat was one of the few items that was not soaking wet on his return. Just a bit damp would imagine it would be fine in normal circumstances.