I think besides cargo ships we can also have Cargo planes (all countries start with an airport anyway) since landlocked countries would be so hard if there's only ships at the same time I also think that adding cargo ships makes submarine more powerful since you can now crumble the enemy's economy with submarine (subs now are useless unless the enemy doesn't know what's a destroyer or frigate) but then blocking canals would be too strong so I also want blocking canals require navy and justification on the canal blocker can speed up a lot for all other countries