In fact, it is often the mapping data which elevates the price of the GPS solution; it must be accurate and updated reasonably frequently. There are, however, several kinds of map, and each is intended for different users, with different needs.

Road users, for example, require that their mapping data contains accurate information about the road network in the region that they will be traveling in, but will not require detailed information about the lie of the land – they do not really worry about the height of hills and so forth.

On the other hand, hiking GPS users might wish to have a detailed map of the terrain, rivers, hills and so forth, and perhaps tracks and trails, but not roads. They might also like to adorn their map with specific icons of things that they find along the way and that they wish to keep a record of – not to mention waypoints; locations to make for on their general route.

Finally, marine users need very specific information relating to the sea bed, navigable channels, and other pieces of maritime data that enables them to navigate safely. Of course, the sea itself is reasonably featureless, but underneath quite some detail is needed to be sure that the boat will not become grounded.

Fishermen also use marine GPS to locate themselves and track the movement of shoals of fish both in real time, and to predict where they will be the next day. The advent of GPS fixing has also meant that co-operative fishing has become much easier, where there are several boats all relaying their locations to each other while they locate the best fishing waters.

Special kinds of marine GPS, known as fishfinders, also combine several functions in one to help fishermen. A fishfinder comprises GPS and also sonar, along with advanced tracking functions and storage for various kinds of fishing and maritime information.