A quick piece I recently made. I was aiming for a more artistic approach.
Rendered in Blender Internal with nodes and the new particle system.
Render time was about a minute.
evilkillerfiggi: The background is actually a gradient from black to dark blue.
In the deep ocean, unless there is a light such a bioluminescent animal (jellyfish),
very little natural light penetrates that deep.
I blurred the jellyfish some, made the ends of the tentacles thinner,
and reworked my node system. The render time was actually about half a minute.