On the east coast is the even larger Hanson Bay, which stretches for the entire length of the island (35 kilometres (22 mi)).This lagoon covers about 160 square kilometres (62 sq mi),[6] and drains several small rivers that rise in the hills at the south end of the island.[7] The central and north part of Chatham Island are mostly flat, with altitudes ranging from a few metres on the northeast and centre to 50 m on the northwest, but with a few scattered hillocks.Chatham Island has an oceanic climate (Koppen: Cfb)[8] characterised by a narrow temperature range and relatively frequent rainfall.[9] The climate is cool, wet and windy, with average high temperatures between 15 and 20 °C (59 and 68 °F) in summer, and between 5 and 10 °C (41 and 50 °F) in July (in the Southern Hemisphere winter).
Volcanic plugs
in north Chatham from 109m Tawirikoko to 99m Puhina, 134m Hemokawa, 151m Hokopoi, 125m Motuariki Hill, 149m Rangitihi, 188m Mt Chudleigh and 178m Korako.