NEW : The man was scuba diving with friends at the time of the attack . NEW : Authorities believe a great white shark inflicted `` massive injuries '' including cuts and lacerations to his body, according to CNN's sister network HLN.
NEW : The man was scuba diving with friends at the time of the attack . NEW : Authorities believe a great white shark inflicted `` massive injuries '' The attack occurred near Rottnest Island in Western Australia .