Authorities are reviewing signage at a popular rock face in Sydney's south after two women died when they were swept out to sea.
The women, both aged in their 30s, were picnicking at Yena Gap before a freak wave swept them off the rocks on the King's Birthday public holiday.
A third woman also swept from the rock shelf is recovering in hospital.
Emergency services were called to Yena Rd at Kurnell about 4.30pm on Monday after reports the women had been swept into the ocean.
NSW Police Marine Area Command chief Joe McNulty said a group of three women and two men had been picnicking in the national park on Botany Bay.
"The people were walking very close to the water's edge and with a low tide the rock platforms are very exposed, very slippery, full of seaweed," he said on Tuesday.
Three of the women were knocked into the water by a large, freak wave, Superintendent McNulty said.
The conditions would give a large wave a "significant extra amount of force" to knock anyone on the platform from their feet and drag them into the water, Supt McNulty said.
It was the second drowning incident at Kurnell in less than a fortnight.
Two Nepalese fishermen were swept off rocks on Cape Solander Drive on May 28 in an area declared a high-risk rock-fishing location where anglers must wear life jackets.
The NSW National Parks and Wildlife Service said it would work with police and review signage at Yena Gap.
It said existing signage warned of dangerous waves, slippery rocks and the need for people venturing onto the rocks to wear a life jacket.
"NPWS will review the signage in place at Yena Gap to see if anything else can be done to ensure people are aware of the risks in this area," it said.
"NPWS understands people want to visit remote locations and aims to ensure visitors are safe when visiting national parks and coastal areas."
Supt McNulty said a warning sign in several languages was already in place in the area, but he urged those "not from a swimming background" to approach waterways with care.
Authorities would also ask for help from community leaders and multicultural media outlets to translate safety messages into other languages and dialects.
One woman was able to be plucked from the water by two members of the group, while a passer-by also helped in the attempted rescue.
Police in a helicopter spotted the women in the water and rescue crews pulled the duo unconscious from the waves.
A rescue boat carrying the women was driven at high speed back to Kurnell, but officers were unable to revive the pair.
Rough sea conditions and the heavy winter clothing worn by the women made the rescue operation more difficult, Supt McNulty said.
