1:1 Flores, Azores, Portugal
The island of Flores in the North Atlantic Ocean.
81 tiles recommended, but not mandatory, as many coastal areas are unreachable with vanilla 25 tiles.
All natural resources are included. Oil is not present in real life, but was included in the map for the sake of playability. It is still scarce, though.
Lots of small streams on the map. Have not tested if they are strong enough for any meaningful hydropower. (Maybe later.) They are mostly intended for the sake of aesthetics.
Scale is 1:1 including height which has no vertical exaggeration. The highest point on Flores is 915m high, which fits well into Cities: Skylines maximum map height of 1024m.
The map has no props of any kind (except trees for forestry). Also, there are no roads or train tracks. You get to design the infrastructure from zero.
Outside connections include ship and airplane paths. There are no train paths going outside the map, as Flores is an island. One (fictional) highway outside connection is located at the south edge of the map for technical purposes (the game doesn’t allow a map without highway connections). For realism, ignore the highway connection.