Latest News Deepens Mystery: Loss of Chinese AIP Sub in 2003

Some Experiment  (color emphasis mine)
January 31, 2014
In April 2003, the Chinese Navy decided to put a large group of its best submarine talent on the same boat as part of an experiment to synergize its naval elite. The result? Within hours of leaving port, the Type 035 Ming III class submarine sank with all hands lost. The Diplomat, January 31, 2014 China’s Deceptively Weak (and Dangerous) Military, Ian Easton


 "The most startling thing about this episode is that [the government] issued a public report. The capacity of the submarine was for 57 men, including 10 officers. The exact cause of the explosion is unclear, but the submarine most likely did not sink."  - Evan Medeiros, China specialist, RAND Corporation.

Chinese submarine Great Wall (No. 361) Type-035AIP (updated Ming III class)

December 19, 2013  - Reuters
In the late spring of 2003, a disabled Chinese submarine was found drifting, partly submerged, in the Bohai Sea off China's northern coast. When the boat was raised, rescuers found all 70 of its crew dead. Their deaths were blamed on “mechanical difficulties,” according to reports at the time in China's state-controlled media. The outcome of any inquiry was never made public.

Since then, submariners all over the world have speculated about what went wrong aboard Ming class submarine number 361, a Chinese copy of an obsolete Russian design. Most agree it was probably a fault with its diesels. The engines either didn't shut down immediately when the submarine submerged, sucking the oxygen out of the hull in minutes, or the suffocating exhaust vented internally rather than outside the hull. Either way, the outcome was catastrophic. 

Naval chief was among victims of No 361 submarine disaster
07 May, 2003 - South China Morning Post
Reports confirm the boat was carrying senior staff in addition to regular crew A senior captain from China's Naval Academy in Qingdao and navy technicians were among the 70 people killed in the Ming Class submarine accident.  The Ming Class submarines carry a crew of 55.

 The Wen Wei Po newspaper quoted senior military sources as saying Senior Captain Cheng Fuming, vice-commander of a naval detachment, was the highest-ranking officer on board submarine No 361, along with observers from the nation's submarine academy.

The report did not fully explain what the 15 extra military personnel were doing on the submarine, other than stating that some of them were trainers from the academy. There has been speculation that they were observing an exercise or testing experimental equipment.

Submarines are always silent and strange.