A hot Christmas Day turned to tragedy as three people drowned and a fourth was missing at North Island beaches.

The deaths prompted a renewed warning from Lifesaving New Zealand for extra care at beaches this summer.

Emergency services at the scene of the incident in Raglan.

A three-year-old boy drowned at the popular Ocean Beach in Hawke's Bay on Friday afternoon during an outing with family and friends.

Members of his family found him in the lagoon and surf lifesavers performed CPR for almost an hour, but were unable to revive him and he died at the scene.

In Waikato, two people drowned and a third was airlifted to hospital after a single incident at remote Ruapuke Beach in Raglan.

Emergency services were called to the remote beach at about 5.30pm to rescue them. By the time they arrived, a woman in her 40s had drowned. The body of a 33-year-old man, who was initially missing, was found by a Coastguard boat at about 6.40 pm.

The third person was pulled from the water in a serious condition and was airlifted to hospital, police said.

A pair of jandals and two beach towels were left behind on the sand as emergency services recovered the bodies.

Hugh Davison, Waikato duty manager for St John says CPR was performed on all three people during the rescue and recovery mission.

"Sadly it was one of those things we've not been able to do any more about."

Ruapuke Beach is south of Raglan near a camping ground, accessible via a gravel road. It is not patrolled.

Long-time resident Caroline Swann recalled eight drownings at the beach in recent years.

"It's a sad day for our district. It's another drowning," she says.

Meanwhile at Castlecliff Beach, near Whanganui, a 17-year-old youth remains missing on Christmas evening after he was swept out to sea in a rip while swimming about 3.55pm.

Inspector Gini Welch, of Whanganui police, said the search was called off around 8pm as visibility became a problem, but would resume on Boxing Day morning.

"We have wound up tonight, but we will recommence in the morning with both water and shoreline searches. At this stage, we are still really hopeful of finding our young man alive."

Lifesaving New Zealand national manager Alan Mundy says it was a sad surprise to hear about Christmas Day's grim toll.

"You are taking your safety into your hands when you hop in the water. Our environment out there is really unpredictable. You need to be a really good swimmer to keep yourself safe, especially if you do get out into a rip.

"We may all think we are good swimmers, but unless you have been in a pool in the last six months, you really aren't equipped to look after your self."

Alan says the warmer weather was drawing eager swimmers to the shoreline, with many lifesaving patrols extending their hours to cater for the numbers.

People getting caught in rips was often down people not being vigilant when entering the water, he says.

"The problem is we think the sea is our back yard, we have got this familiarity which, a lot of the time, is not warranted.

"People don't know about the rips, they don't know about the danger, and as a result, we get people dying in such tragic ways."

Mundy said ensuring people did not swim alone was key to avoiding a disaster.

"People need to think twice about going into the water. If you get into trouble, what is your plan B? If your plan B is you can swim, make sure you actually can."

And Senior Sergeant Bruce Adams from the Police National Dive Squad added: "Christmas day has turned to tragedy. These events are devastating for all involved and our thoughts go to family and friends, and those working to resolve the cases."

He said people need to keep an eye on conditions and changes in water and weather and need to stay well within their abilities, treat the water with respect and caution and avoid alcohol.

"Our beaches, rivers and lakes become more inviting as the holiday period and summer temperatures approach, but we urge everyone to be cautious before taking the plunge," he says.

"Being safety conscious takes a little time but it's worth it. These are avoidable tragedies, they are not accidents."

By Christmas Eve, 93 people had drowned this year, which was one more than last year's total and eight more than this time last year.