the great migration (4 years and 205 days ago)
No external sources used.
Chopped out the "jelly fish" from the source, the rest is PS.
How the underwater scene is made? - loads of tutorials on this online. The ship wreck is pen tool (see sbs) plus filters, mostly Wind and Gausian Blur. The rest - see sbs :)
EDIT: To all of you lucky ones who know russian (hehe), here are the two tutorials used for the underwater scene:
the water http://zerolayer.ru/2007/04/25/pod_vodojj.html
the rocks http://zerolayer.ru/2007/05/01/sozdaem_realistichnye_skaly_k_scene_pod_vodojj.html (5 years and 3119 days ago)