The 15th Northern Rivers Lancers Regiment was undertaking training manouvres at Stockton on 8 March 1954. The flotilla headed out to sea from Wave Trap Beach near Camp Shortland to the Mungo Brush area to the north, near Port Stephens. Rising bad weather and high seas lead to the sinking of five LVT(a)4s, one LVT4, and two DUKWs, with three lives lost. One of the LVT4s has been located underwater in 30 metres, and is the focus of limited recreational diving visitation. This was a significant peacetime loss of life and equipment.
The LVTs, short for Landing Vehicle Tracked Mk IV, were amphibious assault vehicles built during 1943-5, and first used in the Pacific Theatre during World War II. They were nicknamed the "Water Buffalo".