uss "john p. kennedy", the former wooden sailing ship "sea nymph", was a supply ship of the us navy. she was purchased at new york city in 1853 to participate in an expedition to the north pacific ocean to explore for commercial and naval purposes waters in the area of the bering straits and the china seas, which were "frequented by american whale ships and trading vessels in their routes between the united states and china." the expedition, under commander cadwalader ringgold, besides supply ship "john p. kennedy", consisted of sloop-of-war (flagship), brig , schooner , and bark .