614 cubic metres per second

Is how much water flows out of the Clutha River in Otago, on average. It's the biggest river in NZ by annual discharge... I can't actually find a comparable figure for the Waikato River, but I imagine it's reasonably close.

For comparison, the "mighty" Murray River in Aus averages 767 cubic metres per second, but drains a slightly larger area of around 1 million km2 (as opposed to the Clutha's ~22 thousand km2!).