Paradox Development Studio has announced the release date for the upcoming Mare Nostrum expansion set for Europa Universalis IV.

The seafaring-focused expansion will launch on April 5th for PC, Mac, and Linux. Featured above, a new developer diary was released with  Creative Director Johan Andersson talking up some of the key changes made in the expansion.

Mare Nostrum adds lots of new features to the empire builder, including new options for the merchant republics. These financially-focused states can now create Trade Leagues, combining their commercial prowess in both a military and a mercantile alliance.

The expansion also adds the new mercenary options with greater control over the naval-themed missions, the chance to rent your armies as condottieri, and even the ability to share maps with your neighbors.

Alongside the release of the expansion comes a massive free update for the core of Europa Universalis IV, on the same day. This big patch will add new features, which you can read about below:

• Map Expansion: Greater detail to Ireland and sub-Saharan African, especially in the Congo and East Central Africa, and new “States and Territories” system
• Espionage Reworking: Your diplomats can now build spy networks in enemy nations, from where you can fabricate claims on enemy holdings or undermine them from within.
• Interface improvements: Better tooltips overall, and naval blockades are now more obvious on the map
• Naval Combat Changes: better morale system and increased chance to capture enemy vessels
• And even more changes to game balance, AI and modding triggers

In case you missed our review for Europa Universalis IV, you can find that here (we highly recommend it).