No Ditch Between New Zealand and Australia—It's the Tasman Sea

There is no ditch, trench, or canal separating New Zealand and Australia. They are divided by the Tasman Sea—a marginal sea of the South Pacific Ocean.

Key Facts

• Width: ~2,000 km (1,250 mi) at narrowest (Tasmania to South Island) to ~2,250 km (Sydney to NZ North Island).
• Depth: Average ~1,600 m; max ~5,500 m (Tasman Basin).
• Name: Honors Dutch explorer Abel Tasman, first European to sight NZ (1642) and Tasmania (1642).
• Significance: Major shipping route, rich fisheries, distinct marine ecosystems, and a formidable barrier that shaped the separate evolution of NZ's unique flora/fauna (no native land mammals except bats).

The term "The Ditch" is colloquial slang (especially among Australians and New Zealanders) for the Tasman Sea—akin to "The Pond" for the Atlantic. It's a humorous understatement for a vast, often rough ocean crossing, not a geographic feature.