If you’re lost in the wilderness and have a clear plastic bottle of water, you can start a fire by using it as a makeshift magnifying glass. This will only work on a sunny day, but it is a cool way to start a fire.
Here’s a technique you can use to start a fire for survival if you having nothing but a water bottle and a bright sunny day. If you like survival and fire-making techniques, this video is a must see! http://www.thekingofrandom.com