The Hikurangi Trough (previously known as the Hikurangi Trench)[1][a] is a sea floor feature of the Pacific Ocean off the north-east South Island and the east coast of the North Island of New Zealand. It has been forming for about 25 million years and is turbidite-filled, particularly in its south. This characteristic can be used to distinguish it from the sediment-poor and deeper Kermadec Trench, which is its continuation to the north. Sediment currently passing through the trough represents about 0.5% of the total sediment input to the world oceans. The trough has deep-sea chemosynthetic ecosystems that are unique.
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