Exchange between the Tasman and Pacific


Cook Strait, the waterway between New Zealand’s two main islands, influences a range of themes of relevance to society and the environment.  The strength of this influence is in part a function of the physical oceanography of the waters running through the Strait.

Stevens, CL,  M.J. Smith, B. Grant, C.L. Stewart,T. Divett, 2012,  Tidal Stream Energy Extraction in a Large Deep Strait: the Karori Rip, Cook Strait, Continental Shelf Research, 33: 100-109. , DOI: 10.1016/j.csr.2011.11.012. (*list of most downloaded papers April 2012)

The Strait is around 25 km wide at its narrowest point, and over 300 m deep in places.  Furthermore, it is subject to spring tidal currents in excess of 2 m/s and occasionally subject to surface waves in excess of 10 m in wave height.  There is evidence the Strait should, from an oceanographic perspective at least, be considered as one of the great Straits of the world.  It is comparable through both similarities and differences with the Straits of Gibraltar, Messina, Bosphorus, Bering, Torres, Magellan, Hudson, Bass, Malacca and others. 

Cook Strait is many things to many groups. As well as its high cultural and tourist value, it supports fisheries and sustains substantial ferry and commercial shipping. From the energy perspective it contains potential for marine energy as well as containing a vulnerable link in the chain transporting electricity from one island to the other. In addition it provides a substantial control on New Zealand’s coastal oceanography, which in turn influences coastal ecosystems. Despite this, beyond general knowledge of tides, little is known about the details of the oceanography of the Strait.