Historian Paul Moon nearly killed by freak wave while researching Waikato River book

Historian Paul Moon was pulled into the Tasman Sea at Port Waikato by a freak wave while researching his new book The Waikato: A History of New Zealand's Greatest River. Image / supplied

A freak wave near the mouth of the Waikato River nearly brought the end to historian Paul Moon.

He was exploring the rock shelves just to the south of Port Waikato, nearing the end of three years research for a book on the mighty river.

"One moment, I was standing at the base of a small cliff, and the next moment, a shoulder-high wave knocked me down and pulled me into the sea."

He knew the dangers of the turbulent Tasman Sea, but believed he was high enough up the rocks to escape the waves.

"It was just a bit of bad luck. It all happened so quickly. After only about two or three seconds in the water another wave knocked me back onto the ledge and I was able to scramble away."

That experience in July 2016 was one of the more "risky" ones in three years of travelling almost 10,000km along the route of the river and exploring its surrounds and history, he said.

The Waikato: A History of New Zealand's Greatest River, is a 455-page book, which traces the history of the river, the events that have occurred along its path, and the lives of the people who have lived in and around the Waikato.

"It starts with the geology, why the river ends up where it does. For example, it used to end up in Thames, but some dramatic convulsions led to its current shape."

The book then goes into the social and cultural history of the river, and the many peoples who made it home.

From Māori to early European settlers, it has been a source of food, leisure and even transport.

"It is one of the most varied rivers in the country covering all types of settlements, from tiny communities to large cities, and also in terms of geographical features, from the snow to the surf, and everything in between.

"It covers the different people who have relied on it, their dynamic relationships with it."

For farmers it has been a source of irrigation, but also flooding.

"One thing coming through from each person living there, is that the Waikato has numerous personalities. They call it their 'stretch' of river. It is not one entity, but numerous little bits joined together."

There was now real concern about the health of New Zealand's rivers, and especially the Waikato.

"People do what they can to make a living, but at some point it has effects on others. The hydro power stations and damming of the river completely changed the cycle of the water."

From the 1890s to 1920s there were attempts to make the river more "European", by planting willows along the banks.

"People then thought it would make the river more attractive.

"We can see where things went wrong [with the river], and then the efforts people have made to change that more recently."