库克海峡（Cook Strait）位于新西兰北岛、南岛之间，取名自英国探险家詹姆斯·库克。他是第一位航行通过这海峡的欧洲人（1770年初）。海峡北边是北岛的惠灵顿，南边是南岛的马尔堡峡湾和克劳迪湾。

库克海峡西边是北岛的两个大海湾黄金湾和塔斯曼湾，由此逐渐弯曲通向卡皮蒂海岸和南德兰勒奇岸湾。海峡东边的南岛海湾向西南延伸到坎贝尔角。北岛的南岸比较短，沿帕利斯尔湾终止于帕利斯尔角。

海峡最窄处仅23公里。好天气时，两岛在此隔着海峡可以轻易互望。就海峡两岸的纬度而言，南岛最北点还低于北岛最南点。海峡平均水深128公尺，峡内经常风强浪大。有一渡轮来往于南岛皮克顿与北岛惠灵顿之间，单向航程约3小时。

Cook Strait lies between the North and South Islands of New Zealand. It connects the Tasman Sea on the northwest with the South Pacific Ocean on the southeast, and runs next to the capital city, Wellington. It is 22 kilometres (14 mi) wide at its narrowest point, and is considered one of the most dangerous and unpredictable waters in the world.