Hey guys so I have a handhled Gps it is made for fishing and Hunting and I just read the manual today and I found out I can upload topo maps in from a program I can buy and it will give me a topo map of the whole lake such as drop offs flats road beds all underwater structure. Just wondering if anyone has ever done this to find fish??

If the lake or reservoir you are targeting is online, chances are you will be able to find what you need there, without having to buy expensive software for your GPS. If you can't find a good hydrographic map of your lake online, chances are any software package you buy won't have it either. But that's not cast in stone. I use a hand held unit as well, but mainly for marking productive spots and/or structure to fish. I study lake maps ahead of my fishing date. Then I use the sonar to locate structure indicated on the maps. If productive, that's where I drop a waypoint on the GPS.

I use my handheld for marking / relocating spots, works great.