bring the GPS with you!
I like doing hiking very much. But sometime it is very easy to get lost in big parks or in the mountain. I was strongly recommended to bring GPS tracking with me when I go for hiking. You know, in America, everywhere it is so wide but there are not so many people around. Not like China, every place you go, it is full of people.
GPS tracking is also necessary stuff for mountain climbers. When you got lost or were in danger, you can call for help and tell people the exact place where you were. The most dangerous thing is that when you try to all for help, but the battery was over or the wave could not get any signals. In such time, you could take full use of the GPS tracking and try to go to some safe place.