Sailors of the Chinese Navy "Peace Ark" hospital ship stand at attention upon arrival in Puntarenas, Costa Rica, Nov. 23, 2011. The Chinese Navy "Peace Ark" hospital ship arrived in Puntarenas on Nov. 23, starting a seven-day visit in Costa Rica, the last stop of its four-nation goodwill visit to the Caribbeans and Central America. [Photo/Xinhua]