Various groups of Pākehā arrived in this country between 1800 and 1840, and for different reasons. These groups included explorers (although they existed before the 19th century), sealers, whalers, traders, and missionaries. All of these groups had different goals and therefore varying effects on the local Māori population. Explorers mapped the country and announced its existence; sealers hunted seals with little effect on local Māori; whalers hunted whales while creating “Pacific hell”; and the missionaries, arriving with the intention of changing Māori, had the greatest impact of all. The first Europeans to visit New Zealand were the explorers. Abel Tasman, arriving in 1642, was the first and James Cook followed in 1769. Although neither voyage took place between 1800 and 1840, Cook's informative journals were the catalyst for future voyages to New Zealand , as they describe in detail the abundance of plant and animal life found here. Because the explorers simply arrived, mapped, and left, their primary impact on Māori was secondary, as many other Pākehā arrived in New Zealand thanks to the information in Cook's journals. The first group of Europeans to be "summoned" by Cook's journal were the seal hunters. . Sealers came from America, Australia and Britain to obtain seal skins and trade them for Chinese tea. This was the first step that connected New Zealand to the global economy. Sealers had very little impact on Māori because of their location: seals congregated near the bottom of the South Island, where virtually no Māori lived. The sealers lived a very hard life because they were deposed and then left to fend for themselves for several years. The seal trade reached its peak between 1803 and 1810, when the main groups of Pākehā arrived in New Zealand. Explorers, although arriving before this time, discovered this country and revealed its existence to others. Seal hunters arrived to make fur hats. Whalers formed the town of Kororareka and missionaries began converting the Māori to Christianity. All of these Pākehā groups affected the local Māori population; however, explorers and sealers had a very small impact, while whalers and missionaries had a greater impact. The intention for change and interaction with large numbers of Māori were the reasons: explorers and sealers were on the fringes and had little or no contact with Māori. The whalers, on the other hand, had a lot of contact with the Maori, as they used them to help them process the whales, and the missionaries, whose intention was to convert the "savages" to Christianity, had a great effect due of their objective..