Mangrove was constructed by Crescent Shipyard in Elizabethport, New Jersey, for the United States Lighthouse Board and was completed in 1897.

[1][2] Upon commissioning, Mangrove was assigned to the Seventh Lighthouse District, with her home port at Key West, Florida.

[1] After USS Maine – a United States Navy second-class battleship – exploded and sank while at anchor in the harbor at Havana, Cuba, on the evening of 15 February 1898, Mangrove transported wounded survivors of the disaster to Key West.

[1] In March 1898, while anchored in Havana Harbor, she served as a site for the U.S. Navy court of inquiry into the loss of Maine.

[1] She later made a voyage in which she carried guns salvaged from Maine′s wreck[1] and civilians evacuating Cuba to the United States as the Spanish–American War broke out[1] in April 1898.

Under orders to support a Cuban military expedition aboard the schooners Dellie and Ellen F. Adams at Cayo Francés in the Bay of Buena Vista on the north-central coast of Cuba,[3] Mangrove arrived at Cayo Francés on 12 August 1898 to find no sign of the schooners or the expedition.

[4] Mangrove made an attempt to reach Caibarién on the afternoon of 13 August, but returned to Cayo Francés due to unfavorable tides.

[3] At 11:25, Mangrove reversed course, steaming south and east and engaging the larger gunboat with her starboard 6-pounder, firing continuously with that gun until 11:45.

Given the hull classification symbol WAGL-232,[1][2] she operated as a buoy tender in naval service,[1] and by 1945 she was armed with two Oerlikon 20 mm cannon mounts.