Terrain Bonuses and Penalties Question

[unmerged(72467)]

I've been playing EU 3 for quite a while and, before that, EU 2 and Hearts of Iron 1. It just occurred to me to ask: I've been having trouble understanding the map in EU 3 when it comes to mountains, rivers, etc. I remember in the days of HOI 1 that mountainous terrain would be grey and rivers were clearly delineated between provinces. By contrast, in EU 3 it is very common for rivers to go right through a province, and I'm not even sure if mountains affect penalties at all (or are much less detectable). How can I judge where I will get those nasty -5 river crossing penalties? How can I tell whether I'll get -1 or -5 (or both) when a river is involved. If a river runs straight through a province, does that mean I'd get a -5 regardless of whether I attack the province or am attacking FROM the province? Etc etc.

These may be stupid questions, but I've consistently been unable to figure it out. I gave a cursory look with google and the search engine for the forums here, and was unable to find something that'd answer this issue. If I missed an obvious thread, do please link me to it.

Thanks ahead of time, guys!

 

[DDRJake]

If you hover over a province in terrain mapmode it will tell you the different kinds of terrain there and the %chance that a battle will be fought in that terrain. In the Swiss alps it's a 100% chance of mointains (-5 penalty for the attacker) but some lands are, for example, 80% plains (no penalty) and 20% forests (small penalty) so there is an 80% chance there will be no penalty for the attacker and a 20% chance of the small forest penalty.

As for the -1 river penalty, I see no rhyme or reason to it. Identical battles can have the river penalty one time and not have it the next whether there's a river in the way or not.

 

[Ranger Blue]

I'd also like to add (although you probably already know) that it's only possible to get terrain penalties when attacking, defenders will never have any.