Where are we, who has the chart?

On land the options of where to drive is really based upon roads that are available.  You might choose to go by interstate, two lane back roads or try for the dirt option but you are basely going where someone else has gone before you.  It makes decision making a little easier because you are following a path and your decisions are turn left/right or change roads.  Using a GPS in the car is nice because you are really never lost and the system will recalculate your route if you put in a final destination.

For boating there are not a lot of common points with land navigation.  You can use GPS to calculate your route but there are not defined roads so when it calculates sometimes it can take over areas you might want to avoid.  The maps/charts for marine navigation will show depth of the water, make sure you check if it is high tide or low time numbers.  The charts will also show items and other items you might want to avoid.