It's kind of surprising the differences in what people consider a "survival kit" to begin with. Here's a couple of considerations:
1. Weight, if a person needs the kit, then they shouldn't be moving around (they're lost or injured or both), it's getting
to the situation where you suddenly need the kit that makes the weight matter. A heavier kit is a better bet boating/canoeing than hiking.
2. The situation you're in. Chances are the more familiar you are with your environment, the less "survival" gear you'll require. Cultures who live in nature are usually quite adept at living
with nature. Learn from them. It's like that other posting with the story about the guide in the Amazon, "you're not lost, you're right here" to the guide, they're right at home because he's comfortable in the environment. If you're a person who's spent your entire life in an urban environment and decided to take on some extensive wilderness trek, well first off...good! but secondly, familiarize yourself with what challenges that environment will throw at you and what you'll need to deal with them. (Even water that's a little bad can equal diarrhea which leads to dehydration very quickly. The individual begins to feel dehydrated and drinks more water!) That's just one for instance, we could probably go on ad nauseum, but it's essential for a person to know their terrain and environment before they leave home, then the survival kit will be properly packed. Once you're out there, it's too late. Another good rule of thumb...weight factor notwithstanding....is that it's better to have something and not need it than to need something and not have it.
Just a couple of thoughts

Bookmarks