Waihopai Valley is an area near Blenheim in the Marlborough region of the South Island of New Zealand.
The Government Communications Security Bureau operates what it describes as a satellite communications monitoring facility in the Waihopai Valley, which it calls GCSB Waihopai.
It has been identified as being a part of ECHELON, the worldwide network of signals interception facilities run by the UKUSA consortium of intelligence agencies.
The lower Waihopai, as it runs into the Wairau Valley, has a number of vineyards.
[1] From 1925 to 1927 small hydroelectric power station was built in the valley.