For some people, surfing is just a laid-back past-time, something that makes them happy.
However, for others, it makes them angry and violent.
It's known as 'surf rage' - and it often arises when surfers, protective of their local surf, end up competing for waves with new-comers.
The conflict can lead to acts of intimidation and even assault.
Massey University Kaupapa Māori Psychology Lecturer, Jhan Gavala (Ngāti Kawau/Ngāti Ruamahue/Ngāi Tūpango), is an avid surfer.
Having seen - and experienced - the behaviour, he is looking to find out why some surfers erupt in anger, and what can be done about it.
"I'm keen to find out what psychological and cultural factors are associated with surf rage," he says.
"By looking at how and why localism appears in surfing communities, I might be able to get a greater understanding of surf rage and how to overcome such behaviour."
Mr Gavala's PhD study will look at 'localism' at major surf breaks around the country. He's keen to talk to all types of surfers to hear about their experiences and talk to locals about what makes them protective of their patch.
"What sparks or leads to surf rage is an infraction of the protocols around surfing for instance, dropping in on another surfer. Once they might get a warning, twice they get told to get out and then there's aggressiveness," he says.
"As a psychologist, I want to look at the personal dispositions of surfers about what leads to people calling someone out of the surf break because the surf breaks are public space - no one owns them."
He plans on observing surfers from in their natural habitat - surf breaks. As well as this, he will keep an eye out on the beach for anything he thinks would constitute surf rage or intimidation or general unfriendliness.
Mr Gavala says some may think his research is just an excuse to go surfing but he says there is a serious side.
"Along with understanding this complex human behaviour, I'm really interested in using surfing as an intervention to deal with all kinds of psychological challenges and stresses."
As a Māori surfer, his research will also look at the origins of Māori surfing and the possibility of rekindling the craft of Māori surf board building as a therapy programme.
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