It was the earliest of the line of 6 calcalkalic volcanoes, the largest of which is Mount Pirongia (the others are at Kakepuku, Te Kawa, Tokanui, Waikeria and probably Puketotara).

One says that, a long time ago, Karewa was the husband of Karioi, but he flirted with her sister, Pirongia, and was cast into the sea as the offshore rock named by Captain James Cook as Gannet Island.

[12] Among these was the tohunga Rakatāura / Hape, who ascended Karioi and established a tūāhupapa (sacred altar) near the peak, and gave the mountain its name.

[12] Raglan County Hills and Sea 1876–1976[13] (page 17) describes the start of European history - “The sails of Abel Tasman's two ships were seen not long before noon on 28 December 1642. .

"on the 28th in the morning, at daybreak, set sail again, shaped our course east in order to ascertain whether the aforementioned land which we had seen in 40 degrees, extends still further northward or whether it falls away to eastward.

The astute Donald McLean, whom Governor Grey had appointed Chief Land Purchase Commissioner in 1853, began negotiations with the west coast tribes almost immediately.

In the 8 months from January to August, 1854, he arranged the purchase of more than 40,000 acres of native land in the present County area.

On the day following the first payment on Wharauroa, McLean handed over a similar sum in gold to "the chiefs and people of Whaingaroa" as a deposit on the Karioi Block.

Here the boundary ran NE in a straight line toward Te Mata where it met the Opotoru Stream and followed it northward for about 3 miles.

18 months later, on 5 November 1855 (the day on which the last of the £575 purchase money was paid over) 65 of them, including about a dozen boys, signed the deed or affixed their marks in the presence of John Rogan and James Wallis.

"These lands," read the document in part, "we have now entirely given up to Victoria the Queen of England [sic] in the broad light of this day and for ever; with its creeks, its rivers, its streams, its timber and stones."

“The price paid for the Karioi Block (which amounted to 11½d an acre) was in keeping with the Government's view of native land values in the middle '50s, particularly in this instance, when the extent of mountainous terrain was taken into account.

From the heavily forested summit of Karioi Mountain, steep-sided ridges and ravines descended on both seaward and landward sides.

It was soon taken up, and the council, quick to see the advantages of bringing in more people, urged the Waste Lands Board to make other blocks available.

The Waste Lands Board was also asked to provide the means to make roads to the Homestead selections and, by 1883, this work was under way.

By mid-1953 the [Whaanga] road was almost completed, though metalling was not done for 2 years.” Although the on-line history of the summit trig mark only dates back to 1995,[15] it was first surveyed by Laurence Cussen,[16] probably not long after 1876.

In 1928, a fire swept through Te Hutewai, the flames destroying vegetation — and a sawmill — along the entire strip of land between Ruapuke and Raglan.

The main chemicals are silica (47-60%) and alumina (12-20%)[26] Fifteen lava flows make up the 150 m (490 ft) cliffs of the Gorge showing many large augite crystals (phenocrysts) up to 15 mm (0.59 in).

[27] The coastal terrace, above the boulder beach, has remnants of the contact between the early volcanic cones of Karioi and a shallow sea margin, with shells and carbonised logs exposed.

[32] The mountain is unique in being the most northerly on the west coast with a native rainforest sequence from sea level to montane flora.

[33] Whaingaroa's native vegetation used to consist of podocarp rainforest dominated by tōtara, mataī, rimu, kahikatea, rata, black maire and tree ferns.

[34] Despite damage, distinct plant communities (tree fern, ridge, lowland, valley floor, boulder slope, coastal and montane exposed and sheltered) remain.

Cold air drainage on valley floors creates some of the conditions occurring in montane areas e.g., high relative humidity, low evaporative demand, and less sun.

Kiekie thrives in dense tangles in exposed positions and pūriri and nīkau palm are more common on the sea side.

Although brightly coloured and active during the day, they are very well camouflaged and hard to spot in the manuka and kanuka where they mainly live.

"[39] Since a low point in the 1970s, DoC has done a lot to restore Karioi by periodically reducing numbers of introduced animals through eradication programmes.

They didn't achieve residual trap catch rates (RTC) below 5%, so most of Karioi now has aerial drops of 1080 poison at about 5 yearly intervals.

[42] The interval was determined by monitoring of 96 kohekohe, 43 kamahi and 8 Hall's totara, which had been tagged and were assessed annually for change in foliage cover, possum browse and trunk use.

Other steps and chains would be useful, especially after wet weather, but there are plenty of tree roots to grasp hold of on the other shorter near vertical sections.

The Summit is topped with a small radio relay station powered by solar panels, a helicopter pad and a wind generator.