We were in New Zealand this past October -- it rained 8 out of 12 days. I was using 120 film and kept it in ziplock bags. The plastic canisters for 35mm is an added protection. An outfitting shop should have small bags probably waterproof that clip to a belt. Find one the size that will work for you. That would provide easy access without having to go into a backpack when you want to change rolls.