It appears the Herc flew South from Townsville and completed airwork, including missed approaches, as Proserpine (Whitsunday Coast), Mackay and Rockhampton Airports, before it then returned up to Townsville.
168075 was heard to be using the radio callsign of "Sumo 86".
Of interest, also on Saturday 17 July, fellow USMC Lockheed KC-130J Hercules 169227 (Tail Code QD-9227) was photographed visiting Cairns Airport while also on a flight out of and back to Townsville as "Sumo 87".
These two Hercs are based at Townsville in support of joint Military Exercise Talisman Sabre 2021 (TS21) and are flown by the Marine Aerial Refueller Transport Squadron 152 (VMGR-152) the "Sumos".
Sincere thanks to the local plane spotters for taking the time to capture and send through these great photos!
Photos taken by James Kirk and Jonathan Williams ©