"Huntington" was detached from the Reserve Force and placed in full commission on 5 April 1917. She departed Mare Island on 11 May and steamed to Pensacola, Florida, via the Panama Canal. Detached from the Pacific Fleet after her arrival in Florida on 28 May, she spent the next two months at the Naval Air Station Pensacola, engaging in a series of important early experiments with balloons and seaplanes launched from the deck. The cruiser then sailed for Hampton Roads on 1 August and arrived New York five days later. There, "Huntington" formed with a convoy of six troopships bound for France departing on 8 September. "En route", several balloon observation flights were made, and on one of these on 17 September, the balloon was forced down by a squall while being brought back on board and the observer, Lieutenant (jg) Henry W. Hoyt, was knocked out of the basket and caught underwater entangled in its rigging. Seeing the emergency, shipfitter Patrick McGunigal jumped overboard to release the crewman from the balloon basket, by then overturned and underwater. For his heroic action, McGunigal was awarded World War I's 3rd Medal of Honor. The day after the rescue, the convoy was turned over to American destroyers in European waters; and "Huntington" steamed back to Hampton Roads, arriving 30 September.