, I live in Juneau which is considered a Coastal Rainforest. Survived the hike in heavy rain, nothing got wet in the bag. I would still recommend a zippered electronics case or waterproof case just in case, but overall I was really impressed. Also used on a 6 hour hike to a local glacier, just the right size for snacks, first aid kit and an extra (not bulky) layer. I clip my water bottle to my shoulder strap to maximize space.