Kailua Bay
Kailua Bay on the O’ahu island, Hawaii is one of the prettiest places on Earth and it translates well into Cities Skylines. Lots of finetuning went into this map to make it both accurate and playable. There are a couple of other maps of Kailua on Steam but they’re all missing a big piece of land that was missing in the heightmap data. The main tunnel to Honolulu had to be replaced with a mountain pass because you can’t build tunnels in the map editor, but other than that and the fictitious train line the map is quite accurate, including the original freeways and intersections.
This map is scaled down to 3/4th of the original size for gameplay purposes. This way it’s well playable without mods, and with the 25-tile unlocker all interesting parts of the map are playable.