Greymouth is the largest town in the West Coast region in the South Island of New Zealand, and the seat of the Grey District Council. The popul…Greymouth is the largest town in the West Coast region in the South Island of New Zealand, and the seat of the Grey District Council. The population of the whole Grey District is 14,800, which accounts for 43% of the West Coast's inhabitants. The Greymouth urban area had an estimated population of 8,640. A large proportion of the District, 65%, is part of the Conservation Estate owned and managed by the Department of Conservation making Greymouth a natural centre for walkers and trampers.