All images with Canon 1D Mk III, EF 70-200mm f/4L, hand held
The top and middle images show a single jellyfish and the green/black swirls are reflections on the surface of the water. To optimize the images, I worked a little in Adobe Camera Raw 5.4 and then sent the images to Photoshop. Shooting into the water which was heavily laden with particulates necessitated a quick Dust and Scratches filter to clean up the water.
I added another layer and ran the Topaz Adjust plug-in (www.TopazLabs.com) to add a little depth, contrast, and a hint of saturation. Back in Photoshop proper I changed the Topaz layer blend mode to Soft Light and then ran a little High Radius Low Amount sharpening to add shape and form.
I finally decided to do a little more clean up with the Spot Healing Brush.
On the bottom image, I simply launched the Filter Gallery to see if anything looked fun. I ended up using the Plastic Wrap filter and then reducing the layer opacity. Playing in PS never hurt anyone (as long as it was non-destructive.)