A cousin of Sonny Fai has spoken of how the New Zealand Warriors player saved him and other family members from an ocean rip before disappearing in the surf.

Fai, 20, disappeared off Bethells Beach near Auckland late last Sunday after going to the aid of family who got into trouble in the surf.

Cousin James Kaisarika, 24, from Sydney, was among a group including Fai's brother Gillesbie, 13, James's brother Tom, 16, cousin Lafoga Faraimo, 21, and Lafoga's brother Tone, 19, who went to the beach to join in training with Fai, the Sunday Star Times reported.

After training in the sand dunes, the group ended up in the surf with Fai, who had a lifesaving flotation aid.

"We were just trying to catch some waves, and then it started getting deeper and deeper," Kaisarika told the newspaper.

"Sonny was saying to us he could feel the rip was taking us in. He was telling us to go back ... to get out. We turned around but it was too late, we were getting sucked out."

He said Fai and Tom made it out, but returned to the surf when they realised the others were still in trouble.

Fai threw his floatie to the group, who used it to help them swim to shore, but Gillesbie continued to struggle.

"The waves were smashing into us, they were massive," Kaisarika said.

He said Fai, who was yelling at the others to get out of the water, managed to grab Gillesbie and try to swim him back to shore with one arm but both eventually disappeared in the surf.

It took an estimated 10 minutes for the distressed foursome to get to shore and they eventually discovered that Gillesbie had also managed to escape the waves and reach the shore about 50 metres along the beach.

Gillesbie later told his family how Fai had encouraged him to keep fighting, and when they parted he said he would find his own way back to shore.

The family has resolved to keep returning to the beach to search for Fai until he is found.

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