A lot of people think you need Wi-Fi to use a cell phone GPS in the field.
That is not true if the app will download maps "GPS Waypoints Navigator" for android will do that.
In fact I recommend you turn off Wi-Fi and Data to conserve your Phone battery. If left on the phone keeps checking for a connection and will drain the battery in no time. I have a couple of old phones I keep around just for the GPS.
I have some 1000 plus waypoints on my phone. I mark and label everything when I am out prospecting and use the phone GPS to put me back on the exact same spot again. I mark the waypoint name with the bucket number from that spot and later put in a note what came out of that spot. I have a bush out in the desert I return to every time we have a flood. It always has a little something waiting for me.
The learning takes a little time to understand to use GPS waypoints navigator but it is well worth it.