I couldn't find it described in the rules anywhere, but it appears that 2 opposing subs on the same path between outposts engage in combat as they pass. Not sure if this is intended or not. Have some screenshots if they help.

Thx

it's the second bullet point in the combat section. give it another read

Thanks!

Two subs enter. One sub leaves.

Unless no subs leave. (Maryr or equal forces)

Or if both subs leave. (Diplomat in range)

Or if more then two subs enter. (Pirate)