The
Intellimap has a built-in map of the entire world. So if you were to turn-on the unit in say, Cambodia, it would show the river you were on. It also shows major roads, cities, towns, ports, etc.
When in the United States, the map has a more detailed version of major lakes, coastal & great lakes waterways, roads, "points of interest" like restaurants, motels, etc.
Undoubtedly over the years, you have seen the waterproof folding paper "Fishing Hot Spots" maps of a particular fishing location, like Saginaw Bay, Higgins Lake, etc. They make paper maps of these for lakes and rivers all around the country. These maps show drop-offs, structure, boat launches, reefs, etc. and areas to "key-in" on for fishing.
Well, the
Navionics cartridge I mentioned upgrades your GPS to a computerized version of that. Highly, highly detailed maps comprised of data from USGS, Fishing Hot Maps, MDNR, NOAA, and many other sources. You pop the cartridge into your Intellimap, and WALLAH! Instantly has the data for 224 Michigan lakes, bays, and rivers.
Here's their site:
http://www.navionics.com/HotMaps/Default.asp
The GPS itself is very uncomplicated to use. I know it looks intimidating... but I am very un-sophisticated when it comes to electronics, and if I can get the hang of it,
anyone can.