A vessel involved in salvage operations passes near the upturned South Korean ferry &quot;Sewol&quot; in the sea off Jindo April 17, 2014. Rescuers were hammering on the upturned hull of a capsized South Korea ferry on Thursday hoping for a response from hundreds of people, mostly teenage schoolchildren, believed trapped after the vessel started sinking more than 24 hours previously. REUTERS/Kim Kyung-Hoon  (SOUTH KOREA - Tags: DISASTER MARITIME TPX IMAGES OF THE DAY)