Two people died yesterday as they were swept away while trying to cross a flooded river in the Waitakere Ranges.
Police said three in the group of five trampers survived the accident near Cascade Falls. One was rescued and taken to Waitakere Hospital, another who made it to safety was also taken to hospital with minor injuries and the fifth was uninjured.
The flooding was caused by torrential rain, which also sparked evacuations of about 100 people in Piha.
About 20 others were stranded by rising waters on a nearby walking track, "shivering uncontrollably" and huddling together for warmth.
One member of the group, a mountain runner from Canada, ran different tracks until he found a way out that wasn't flooded, so the group could make their way to safety.
In Piha, fire and police personnel evacuated about 100 people from homes around Glenesk, Seaview and Beach Valley Rds when a rising stream threatened to flood properties.
People were evacuated to the nearby surf club and campground.
Piha resident Bevan Hill said the art gallery was flooded as well as the campground.
"There's a lot of people saying they've never seen anything like it. The river coming out on Piha beach is incredible. It's like the Waikato River flowing out there." Hill said there was "water everywhere" and he had water coming in his front door on Garden Rd.
"A lot of wet and soggy campers" were packing items into their cars, and a few tents had ended up underwater.
"It all happened so quickly."
Debbie Leigh from the Piha RSA said people were reporting cars drifting in the floodwaters.
Phil Wallis from the Piha Surf School said friends of his had taken pictures of cars floating in floodwaters, with the water rising up to the sills inside the cars.
Meanwhile, Colin Ennor was among a group of about 20 stranded on Winstone Track off Piha Rd after flash floods cut them off from the carpark.
He said what was meant to be a gentle 30-minute walk to the Kitekite Falls in jandals and T-shirts turned into a "three-hour experience of survival".
The low, nearly dry creek they'd crossed to get to the waterfall had turned to a raging torrent in less than an hour.
"The river had risen so high that there was no way out. The river was above your head if you even tried to get through it."
Ennor and his group banded together with strangers. They spent several hours trying to find a way out.
"Every way we went to walk was completely blocked by flooding."
The group spent an hour trying to find cellphone reception to call for rescue, and only one person's phone was able to get even a single bar.
Police said they eventually found a safe route out of the bush and walked towards Glenesk Rd.
And police said 50 people were caught out by the floodwaters at a wedding venue on Bethells Rd.
The people were at a wedding reception at Flaxmere House. Police and fire attended but did not have to take any action because the water receded.
Auckland Tramping Club president Tony Walton said people should not cross a river if they could not see the bottom or if the water was running faster than walking pace.
"If it's a swollen river you just don't go crossing it."
The MetService forecast for today is occasional rain, with possible downpours in the afternoon or evening. More heavy rain is possible tomorrow.
Several members of a church youth group holidaying at a Piha campground were among about 100 people evacuated yesterday.
A woman who asked not to be named said the floodwaters came in within a matter of a few minutes.
"All of a sudden we looked up to see all this water just flooding towards us. It was so fast.
"It carried down logs and just [flooded] the whole ground in about two minutes.
"We literally just picked ourselves up and got out."
Teen Gideon Hope said he had just finished afternoon devotion when the waters flooded into the hall he was in.
"The water just came in, we couldn't do anything about it.
"It was a bit scary," the Henderson 16-year-old said.
Phil Wallis from the Piha Surf School said he was in the water taking a lesson when the rain started.
"It was horizontal. In almost 40 years here it's the strongest rain in a short period I've seen. You couldn't see the beach.
"Immediately the stream started just pumping out brown water."
A nearby stream that usually didn't have any flowing water transformed into a torrent.
"It was almost a standing wave coming down the beach."
Floodwater began receding by 8pm and all evacuees were able to return to their homes.