Empty scene in Unity needs a bit brighten up, but before I begin, let's clarify and prepare the assets. What are assets? Assets represent any objects that will be used in your project. Not only 3D objects, but all scripts, audio files, textures, images, you name it. And there is going to be lots of assets, so it is important to keep it clean.
In my scene I created folder Objects, which will contain all of the 3D game objects. The player character is entity "player". Therefore I create hierarchy "Objects>Entites>Player". And for the island, "Objects>Levels". Every level will contain object with static model of terrain. From each asset Unity creates an instance in the scene (when object is dragged to the scene). Any changes made in assets will show immediately in the scene.
For better results I added a skybox, downloaded in the asset store provided by Unity. It's also needed to add an Lighting in the inspector. Simply by clicking on Window>Lighting. There is button Scene in the Lighting panel and there is Skybox field.
I will be creating a navigation in the next log.