Variant: The Harbormaster
The Harbormaster is a small rule variation involving the Harbormaster bonus, a victory point bonus akin to Largest Army or Longest Road, and is compatible with virtually any Catan scenario. The Harbormaster was previously published as part of the German Atlantis expansion, as well as a free (though German-only) download from the Catan web site.
With this variation, any settlement bordering a harbor earns one Harbor Point, and any city bordering a harbor earns two Harbor Points. The player with the most Harbor Points, provided that they have at least three, is awarded the Harbormaster bonus, worth two Victory Points.
The use of this variation also increases by one the number of Victory Points needed to win.
Read more about this topic: Catan: Traders & Barbarians