Pavan Ghanasala and Praveen Srikanth, both in their 30s, sacrificed their lives while they were lifting their wives above the water to help them breathe yesterday.

Rangers were in the process of closing access to the sandbar when the two men drowned, according to media reports here.

The two died on the shore despite efforts to resuscitate them after they were swept into deep water off the popular island.

Ghanasala who was a boilermaker had recently arrived in Australia with his family. His two young sons, aged seven and nine, have still not been told of their father's death.

The victims' wives and two other companions, who had attempted the crossing with them, were rescued and taken to hospitals in nearby Rockingham and Fremantle.

They had been picnicking on the island with their children and other family members, who had returned to the mainland by ferry and watched the tragedy unfold from the beach.

Department of Environment and Conservation rangers were in the process of closing public access to the sandbar when the drownings occurred, DEC district manager Mike Meinema said.

They have since closed the sandbar to the public for the rest of the year due to strong afternoon winds forecast for the period.

Permanent signs warning people of the danger of making the 750-metre crossing on the sandbar and advising them to take the ferry were in place on both sides, Meinema said, adding "People will often ignore that advice."

Meinema said DEC staff were "probably caught off guard" by very high visitor numbers yesterday.

The Department would continue to assess the rules for crossing the bar.

"Obviously we don't want deaths occurring so we'll look at what we can do," he said.

"It's an impossible thing, pretty much, to police. Ultimately it comes down to a decision on the individual's part," he said.

Penguin island is a popular diving, snorkelling, swimming and picnicking spot and is known for its colony of Little Penguins.

Rockingham Mayor Barry Sammels fears people will continue to cross the Penguin Island sandbar that claimed two lives yesterday, even if it is permanently closed by authorities.

Sammels told a local newspaper that unless lifeguards or someone monitored the sandbar permanently, people would continue to cross it.

"Unless we have someone standing there and there is a permanent presence to stop people from crossing, we will still have people crossing it," he said.

"We are happy to assist where we can with our rangers and we can put signage up but I do not want people crossing it (the sandbar) no matter what the weather is like.

"We have the same problem every summer."

Sammels said the City of Rockingham would be liaising with the Department of Environment over the next few days to address the problem.

"This has been an ongoing issue and one that we have to address," he said.