You could also make the short distance also hilly and / or jungle to help slow down 2 movers.
I have two concerns. 1) the inner sea is probably pretty tight and violent. 2) how big overall is the map / how big do they want it? It is medieval start so I imagine they want it at least medium? but overall this idea seems like it will be a bigger map and want to make sure they are ok with that.
I have two concerns. 1) the inner sea is probably pretty tight and violent. 2) how big overall is the map / how big do they want it? It is medieval start so I imagine they want it at least medium? but overall this idea seems like it will be a bigger map and want to make sure they are ok with that.