Doing more research on this, I Googled it. What is happening in this picture I thought was interesting and I would share. It is the sub being demagnetized.
http://en.wikipedia.org/wiki/Deperming
"A sea-going metal-hulled ship or submarine, by its very nature, develops a magnetic signature as it travels due to a magneto-mechanical interaction with the Earth's magnetic field. This signature can be exploited by magnetic mines, or facilitate the detection of a submarine by ships or aircraft with magnetic anomaly detection (MAD) equipment. Navies use the deperming procedure, in conjunction with degaussing, as a countermeasure against this."