Coghlan's Camp Soap is concentrated and can be used to clean anything from hair to cooking pots so its ideal for trekking trips. Its also biodegradable, which is essential for use in the outdoors.
Coghlans says:
Effectively cleans anything washable in all water types and temperatures. Great for greasy pots, pans, dishes, utensils, clothing, packs, tents. And, well suited for use on hands, face, body, hair. Free rinsing and environmentally compatible.
Coghlan's Camp Soap is concentrated so a small bottle like this one will do a weeks backpacking if you're careful, it will clean anything from your hair to your cooking pots, so its conveniently the only soap you'll need. Comes in a handy bottle with squirt dispenser.