For my project, I want to transition from a volcano environment to an underwater environment with the twist that the former is made of water and the latter is made of lava/fire. I would like for both environments to feel very calming in terms of mood.
For example, below is a sketch of an initial state.
My transition will probably be started by holding a key (like previous exercises), and I would like to try simulating the ground shaking, and having the camera ‘fall’ down through the terrain. The following is just an idea of how the colors will change (a gradient).
The ending state will be a lava ocean with animated fish and fire bubble particles. 
The following is a mood board:
I don’t have a chosen sound clip yet, but I’m currently thinking of using some kind of spa/relaxing background music in addition to sound effects.