What was the purpose of the map and the traveling?

Iirc, he was trying to get to some sort of rescue station or shelter... maybe where he could send out a signal for help, or come across people who could help him out. This shelter was depicted/ represented by a diamond on the map. The map was helping him chart an unobstructed course through the rocky terrain. I.e.: it showed him a path he could travel that was just flat land and no hills/ mountains.

Hope that helps.

He was trying to get to a seasonal research station.

Before the helicopter crashed he wasn't sure where he was, how far out in BFE. When he got the map from the helicopter, he discovered that there was a seasonal station only several kilometers away, that he might be able to reach on foot. The map helped him plot a course through the mountains with minimal obstacles.