There are smartphone apps that can be almost as useful as a dedicated GPS, but a dedicated GPS has a much more readable screen in the sun and it might use AA batteries. I bought my first smartphone primarily to use as a GPS and gave up on that idea really fast - then bought a Garmin GPS that had a micro SD card slot so I can download maps off the internet and load maps into it. I was amazed how fast the screen on my smartphone burned up the battery. I use rechargeable AA batteries in the GPS, but if I had to I could buy some disposables in a store. Now I only use the smartphone as a wifi device for e-mail and checking the news.