(5 years and 3112 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 3113 days ago)