A man has drowned at a waterfall in Victoria's Grampians National Park.

Key points: Four people have drowned in Victorian waters this festive period

Four people have drowned in Victorian waters this festive period Another person drowned at MacKenzie Falls in January

Another person drowned at MacKenzie Falls in January With many on holidays and a heatwave underway, swimmers are urged to be careful

The 27-year-old from New Zealand fell into the pool at MacKenzie Falls about 5:00pm yesterday and was unable to be saved, police said.

His body was recovered by emergency crews just before 1:00am.

But while police said the man fell, witness Nathan Godwin said the man been swimming at the falls.

"It quickly became apparent that he was in trouble," Mr Godwin said.

"He was trying to grab onto the ledge."

Mr Godwin, who was travelling through Victoria from South Australia, said the man soon disappeared under the water.

"People started jumping in the water to help and someone gave some goggles to see under the water," he said.

"One tourist could potentially make out his body, however, it was too deep."

Mr Godwin said the rescue effort was abandoned over fears others might be "sucked under".

"We all attempted to console his wife, friends," Mr Godwin said.

Another man died at the tourist hotspot in January, and Mr Godwin wants improved signage at the falls to better warn of the dangers.

The latest death is the fourth drowning in Victoria in just three days, after three men died at beaches south-east of Melbourne over Christmas.

On Christmas Eve, a father and son drowned in dangerous surf off Cape Woolamai, on Phillip Island.

The following evening, an abalone diver drowned at Cape Schanck on the Mornington Peninsula.

Dangerous conditions ahead

With many Victorians on holidays and much of the state in the grip of a heatwave, swimmers have been urged to be careful, especially along the coast.

"The biggest killer is the rip," Life Saving Victoria CEO Nigel Taylor said.

He suggested people go to the local pool if conditions at the beach are rough or it is unsupervised, and warned against swimming late in the day.

"If you are thinking of a twilight swim, it's quite likely there'll be no-one on patrol."

He said holidaymakers looking for an inland waterway to swim in should seek out local knowledge about the safest spots to have a dip.

He also reminded those on boats to wear a life jacket at all stages.

"If you are in a boating environment and you think you won't get in trouble, well others have fallen for the same mistake," Mr Taylor said.

There have been 31 drowning in Australia so far this month, Life Saving Victoria said.