The carcass found entangled in ropes on a Chinese beach is reportedly over 17 meters long and unidentifiable. Unidentifiable carcasses often end up getting identified as basking sharks, which decay in a peculiar fashion that leaves them looking like monsters with long necks and small heads. I can't make any certain identification from this photograph, although it has something of a basking shark carcass look to it. Still, if the measurement is accurate, it is one heck of a big shark. 14-15m is usually considered the basking shark record, although there are claims of 20m and more.
Update: Cryptozoologist Markus Hemmler reports this has been identified as a decomposed baleen whale. Darn.