Let’s say your canoe capsizes and all off your handy fire-starting equipment was lost. You still have the rest of your equipment, but no way to start a fire. At this point, most people would spend resign themselves to early nights, and cooking by stovetop. You don’t actually need a fire to enjoy camping, so no need to end the trip early. A few brave people may try to rub sticks together, but even if they did eventually manage to start a fire, they certainly would never want to do it again.
Thankfully, there is another way. Using water and the power of the sun, a fire can be started without any additional equipment. Or magic. Be warned, it takes a lot of patience, and it will hurt your eyes. Sunglasses are recommended.
Start by digging through your food barrel for a clear plastic bag, or plastic wrap. A water bottle may also work, but plastic bags are best.
Fill the bag with water. Find the cleanest water possible, or use water from your filter if you can spare it.
Find a nice clearing with plenty of sun. If it’s cloudy outside, this won’t work. Go back to rubbing sticks together.
Create a pile of very, very fine kindling. A good way to do this is to scrape a dry piece of birch bark into a powdery substance, or use dead grass. If you have a flint, scrape some of this off into the pile as well. Shield the pile from the wind as best you can.
Hold the water bottle between the sun and the kindling until you see a concentrated dot of light. Adjust the bag until the dot becomes a focused beam. This is the part where you’ll want to be wearing sunglasses.
Much like a magnifying glass, the bag of water focuses the light into a beam. By holding it at just the right angle for the right amount of time, enough heat can be generated to start a fire. This takes a lot of patience, and a lot of dots in your vision, but if you stick to it, it can start your fire. It may help to yell at it for support.
A while back I found a paper-sized Fresnel lens, and often bring it on camping trips. Its flat and fits into any of my packs, and is a great camping party-trick that can be used to win bets with my friends. To date, I have won many a beer starting fires without a lighter or match.