Announced yesterday at Gamescom.
DLC 1, Sunken Treasures, available now. Go treasure hunting in the depths of the sea and build your biggest city yet on a huge new continental island.
DLC 2, Botanica, coming September 10th. Turn your city green with a modular botanical garden.
DLC 3, The Passage, coming this winter. Survive the arctic cold and construct your airship fleet.
Also a day and night cycle will be added as a free update on September 10th.