To me you are not far away. It LOOKS high already. Only the background (the islands i think) is too regular spread out. No dynamic in there, nothing where the eye can have a point to identify what it is and how big things are. Maybe some bigger islands and not so many, maybe a ship that the viewer can see and has something to compare sizes. A big tanker for example. We know how big it really is and then can compare how high we must be so that is looks small. Kenwas for example is a master of playing with depth. There we all can learn a lot about that. And Criss3d too, his panoramic landscapes are perfect to study this.

One day your ship comes in - but you're at the airport.