Rudy Bruynius' two-year old daughter Mckayla is in a serious condition after the family was knocked off rocks at the beach while holidaying in Newquay.
Friends are now raising money to help Mr Bruynius' widow Lisinda and the couple's three children.
His death came on a weekend of fatalities off the coast of the UK amid stormy conditions.
A friend of the Bruynius family, Madelein Jansen Van Noordwyk, has set up a crowdfunding page, which has already raised more than Â£13,000.
On the JustGiving site, Lisinda Bruynius said her daughter Mckayla had been moved from the Royal Cornwall Hospital in Truro to the Bristol Children's Hospital. The two-year old's condition was stable during the ambulance journey.
Mrs Bruynius wrote: "Pls continue to pray for my miracle baby...for her to pull through.
"As they can't give me a certain indication of how much brain damage occurred during her time in the water."
The family, from Surrey, were swept out to sea at South Fistral Beach at 17:20 BST on Friday.
An RNLI sea scooter was used to rescue Mrs Bruynius, while a lifeboat was deployed to recover Mr Bruynius and Mckayla. They were flown to hospital where he was pronounced dead.
Police said two other children managed to get back on to the rocks and were located by the coastguard. Mrs Bruynius received hospital treatment for minor injuries.
The RNLI said the sea conditions changed considerably between 16:00 and 17:30 and crews were called to three rescues.
James Instance from Falmouth Coastguard said: "At about 16:00 BST, there were normal conditions.
"By 17:00, the swell had picked up to eight to 10ft and that massive increase in such a short period has caught quite a few people unawares."
Mr Instance warned people to take extra care near the coast.
"What should be an enjoyable experience could so easily take a traumatic turn," he said.
"Please do listen to warnings and stay at a safe distance from the water."
Visitors to the UK coastline have been urged to stay away from areas where surging waves could sweep people off their feet and to be careful of tides, as strong wind conditions mean the sea could reach higher levels than expected.

She had arrived at a running club meeting in Kings Heath when three men demanded she hand over her car keys before using a stun device on her, police said.
She alerted a passing van and the men ran away.  She was left "shaken, bruised and with burns", the club said.
There were similar reports between 5 and 10 February.
Read more Birmingham and Black Country stories.
West Midlands Police said there were six reports of alleged assaults involving "small stun devices" in Moseley, Kings Heath and Acocks Green.
It is not yet clear whether the incidents are linked.
Four teenage boys, two aged 15 and two aged 16, were arrested and bailed in connection with a robbery in Acocks Green on 5 February. Witnesses are being urged to come forward.
A post on Kings Heath Running Club's Facebook page said: "There was a serious incident prior to club run last Thursday.
"It was an attempted car theft by three young men who demanded a runner's car keys.
"She refused and an electric Taser device was used on her during a physical struggle.
"She was shaken, is bruised and has seen a doctor who has assessed the burns left by the Taser.
"This was a random event - the runner took no risks in parking her car on a well-lit road next to the school."
An appeal has been set up to help the family of a man who died after he was swept into the sea by a large wave.
[NEXT_CONCEPT]
A woman was attacked with a stun device during a car-jacking in Birmingham - the sixth such attack in as many days.