The 28-year-old was reportedly surfing near Granites Beach on the Eyre Peninsula west of Adelaide on Thursday when attacked about 7pm.
Witnesses reported seeing the shark attacking him, triggering a search by police with SES and local volunteers.
His body is yet to be found and a search by air, land and sea resumed on Friday morning, South Australia Police said in a statement.
The beach remains closed with members of the public advised to avoid the area.
The man was surfing in the same area where 55-year-old Tod Gendle was killed in October 2023.
Tod Gendle was killed by a shark at Granites Beach in October 2023. (Supplied/AAP PHOTOS)
A 4.2 metre great white was spotted in the water just after he disappeared at the popular South Australian surfing spot.
SA had two other fatal shark attacks that year including that which claimed 46-year-old teacher Simon Baccanello at Walkers Rock Beach west of Adelaide in May.
Khai Cowley, 15 was fatally mauled in a suspected great white attack at Ethel Beach on the Yorke Peninsula in December.
Following Khai's death South Australian Premier Peter Malinauskas said a range of shark deterrents were being investigated but netting the state's remote beaches was impossible.
Shark mitigation and improved first aid responses were announced in November in partnership with Surf Life Saving SA, with the state allocating $500,000 to reducing the risk and impact of shark attacks.
40°C