A 27-year-old man has died of suspected dehydration during a hiking trip at the popular tourist spot, Nature's Window, in Western Australia's Mid West region.

Key points: Friends of the man raised the alarm after he collapsed towards the end of the hike

Friends of the man raised the alarm after he collapsed towards the end of the hike Police said the group had set out with three small bottles of water each

Police said the group had set out with three small bottles of water each Hikers have been urged to be prepared for the effects of heat, dehydration and exertion

The Northam man was with friends when he became distressed and collapsed around 3:00pm on Saturday while completing a hike in Kalbarri National Park, about 485 kilometres north of Perth.

The man was placed under a tree and given water, however police said the group then ran out of water.

A tourist who was a German doctor tried to help resuscitate the man before paramedics and emergency services arrived at the scene, but he could not be revived.

"A man who dies in his mid-twenties in circumstances that possibly could have been avoided is always a tragedy … we certainly feel for his family and friends," WA Police Inspector Garry Kosovich said.

Kalbarri SES are urging hikers to consider the conditions before setting off. ( Facebook: Kalbarri SES )

Police are investigating the circumstances surrounding the man's death, but it is believed he succumbed to dehydration.

"He had just done the 8km walk and he collapsed just before Nature's Window," Kalbarri State Emergency Service local manager Steve Cable said.

"He was almost back to the beginning because the loop [trail] starts and finishes at the same point — he felt unwell and that was it."

Police said the man may not have had enough water or appropriate clothing.

"[The group] set out with three small bottles of water each," Inspector Kosovich said.

"We ask that if you're going to walk in the hot sun in WA that you do have adequate covering for all your body, including your head, and adequate water, as that was possibly not the case in this circumstance," he said.

"I understand that he was a large man and was possibly not in the best physical shape to undertake such a walk, but I'm not sure of his medical background."

Conditions 'quite warm', hotter on trail

Mr Cable said the heat in the region could quickly turn deadly for those unprepared.

Failing to take the heat into consideration can have tragic consequences, the SES says. ( ABC News )

"The thing about Kalbarri where people fall apart is that whatever temperatures are in town — and it was quite warm, 31 degrees — but out there it can be anywhere from 10 to 15 degrees hotter," he said.

He said failing to take the heat, exertion and dehydration into consideration could have tragic consequences.

"Often they don't wear the right attire, they don't have enough water … they try and push it too far and they don't do their homework as far as conditions go," he said.

Mr Cable said that while the recent incident was tragic, many make the journey safely.

"You can do it, you can do it quite safely and comfortably but you have to pick your times and you have to be prepared," he said.

"It's a great walk and it's a great adventure but you just have to be smart about it."

The exact circumstances of the man's death are not yet known, nor whether he had a pre-existing medical condition.

A report is being prepared for the coroner.

Woman, children rescued in bushland

In a separate incident, a woman and two children were rescued in the state's South West on Saturday night after becoming lost in the Jarrahwood State Forest, near Upper Capel.

The woman and her three-year-old and five-year-old children went walking around lunchtime on Saturday but did not return, and did not have a personal locator beacon on them.

They were eventually found fatigued and dehydrated just before 1:00am.

Police said the incident highlighted the importance of carrying extra supplies of water and safety gear, even when people were going on a short walk in bushland.

"In this situation a personal locator beacon could have been used to alert authorities to the fact the woman and children were in danger," a police spokesman said.

"The beacon would not only alert authorities to the situation, but provide the exact coordinates of where the missing stranded people are — which means the time taken to rescue them is a lot less.

"Even highly experienced bushwalkers who are familiar with the area they are in can experience unexpected trouble, so we recommend anyone planning camping or bushwalking activities consider just how important a personal locator beacon can be for them."