An original creature design and 3D sculpt plus experimentation with an underwater render scene in Blender. Light paintover and effects in photoshop.
The biggest challenge was getting the environment in Blender to read well, and running different tests with lighting, caustics, and volumetrics, both in Eevee and Cycles engines to get desired results. Ultimatley, I set up three separate scenes—one for turnaround animation renders in Eevee, one for underwater captures in Cycles, and another for above-surface captures, also in Cycles.
Eevee render in a separate scene for the turnaround.