Environmental arguments aside, plastic bags are one of the most versatile, lightweight, compact and inexpensive pieces of gear in your pack. I never go on a trip without some form of plastic bag tucked away, ready for action. They come in all sorts of sizes but my favorite ones are small sealable sandwich bags, 1 gallon ziplocs, and sometimes large stretchable garbage bags. Storing things in sealable bags is great because moisture stays in, moisture stays out, smells stay in, contents stays organized, and you can see what you have in there without opening it.
I do make use of multi-sized dry bags, especially when I’m kayaking, but sometimes you just can’t argue with the convenience and durability of a sandwich bag. I often use the small bags for things like vitamins and pills, gatorade mix, car keys and other small things that I don’t want getting wet. The medium or larger sized resealable bags often hold my food, seal up my dirty socks or keep trash and food wrappers from attracting animals. Once you get on the trail you never know what else they might come in handy for. We once used large garbage bags for pack covers! We were hiking 4 days on the typically dry trails crossing Zion National Park and we had packed primarily for hot, dry weather. Just our luck it rained on us every single day. Always prepared with layers and jain jackets, but we had not brought along pack covers. Luckily we had stashed large garbage bags in our packs a month earlier and hadn’t taken them out. They fit over our large packs with a little stretching and kept our tent and sleeping bags perfectly dry for the entire trip. Awesome.
In a world of overpriced hiking gear and shiny new products, I often remind myself that the least expensive or significant items can often prove to be the most valuable.