As the high temperatures hit, cooling off in New Zealand rivers is becoming dangerous, with toxic algae detected in watercourses in most regions around the country.
In the lower North Island, poisonous blooms are the most widespread in at least a decade with calls for the public not to be complacent.
Dogs trying to cool off are particularly at risk of ingesting the algae - they like the musty odour but it's as toxic as cobra venom.
“Initially we start seeing weakness through to collapsing and then progresses through to seizures and respiratory paralysis and death,” says Tony Noise, South Wairarapa Veterinary Services.
Waipoua River is particularly dangerous as the algae is washed towards the river's edge.
It's also potentially toxic for people, the council reinforcing the need to monitor children.
“We really encourage people to know what toxic algae looks like. You can imagine a young kid coming down to swim, accidentally gets their hands on the algae, puts their hands in their mouth and they're ingesting that toxin directly,” says Mark Heath, Greater Wellington Regional Council environmental scientist.
The naturally occurring algae has been found from northland to Southland this summer, warmer temperatures increasing growth.
And scientists predict climate change will make it worse.
“It's affected by things like land use and we're looking then again at long term change and there's no silver bullet, nothing we can do in the short term,” Mr Heath says.