After some hesitation I decided to create an underwater backdrop, very light and easy to manage. 

In fact, the goal for this type of environment is to be the base scenario for more complex underwater scenes.

Attention: This scene (including assets) is available only in blend format and it's not suitable for being exported to other programs (due to the particles systems used for ecosystems).

However, you can use the heightmaps in tif format (in the packlist) and use it with the displacemet feature in other programs.

In addition, you can take advantage of all the alpha-masks and textures (in the packlist) to redo, the texturing and ecosystems of the scene.

Notes: The scene include 1 simple terrain, modeled in Gaea and texturized and populated in Blender 3.2 (Render Cycles). 

The scene was populated with 9 (8+1) eco-systems (by ParticleSystems), inside a box that simulates the underwater environment. 

All the assets are in blend bundle and not exportable (1 red coral, 5 anemones, 2 algaes, 5 pebbles, 5 rocks, 4 grass, 10 fishes pics).

Scene powered by the Cycles engine.

Packlist: 1 Blender file, 8 alpha-masks, 6 textures, 1 heightmaps (in tif format), 1 readme.pdf.

Vertices: 1.050.000 Triangles: 2.097.000