USS Oahu - Laid down in 1927 in Shanghai as a River Gunboat for use in the shallow rivers and coastal waters of China, USS Oahu operated as part of the Yangtze Patrol Force from her October 1928 commissioning through December 1941, during the latter part of which she operated in highly contested war zones between the Nationalist Chinese and Imperial Japan.

 Forced to depart China when her homeport at Hankow was in immediate danger of falling to Japanese troops, the Oahu and her crew joined with other river gunboats for a highly dangerous cross-ocean voyage to the Philippines on December 2nd, 1941, arriving in Manila on December 10th. With war having been declared while she was at sea, the Oahu immediately took up defensive operations patrolling Manila Bay and providing fire support for troops fighting on Bataan with her fellow China River Gunboats USS Luzon (PR-7) and USS Mindanao (PR-8) for the next several months. 

http://en.wikipedia.org/wiki/USS_Oahu_(PR-6)

http://wikimapia.org/16261924/Wrecks-of-USS-Oahu-PR-6-USS-Quail-AM-15