The police said that both men were experienced divers, and that they had correctly deployed both an SMB and a flag to alert other water-users to their presence.
The dead man’s buddy was reported to have waved to the speedboat believed to have struck his friend on surfacing to warn of their presence, and to have exchanged words with its driver. It was only after the boat had left the scene that the diver found that his buddy had sustained serious injuries, though it was not clear at which point the impact had occurred or whether the boat-driver had been aware of it.
A passing boat had picked up the divers and taken them to Frankston Pier where, despite intervention by paramedics, the injured man was pronounced dead. A large-scale investigation to track down the speedboat and its driver had ensued.
Under local marine-safety laws, boat-users are required to slow to 5 knots within 100m of a dive-flag or 200m of the shore. It was not clear whether the boat had been exceeding speed limits.