Attached Link: Slow Ascent

The ocean floor reflecting up would actually be realistic, although I can understand you dilema, you make anything glass-like in Bryce, and it is automatically reflective, frustrating when you don't want it to be! Terrain - washed out; Take down the ambience, it shouldn't be any higher than 15, & in a scene like this, you may be able to get away with zero. After that, then start taking down the diffusion, bit by bit, while test rendering, until you get what you like. Bubbles - Since you most likely wouldn't see their shadows anywhere anyways, you could disable all their shadow properties. I do this with anything I can, speeds up rendering. Also, (imho), pretty much never use the setting; "Sky Lab>Atmosphere>Volumetric World". This feature unnecessarily increases render times by way too much. Just use haze/fog settings. (fyi) AgentSmith

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