We travelled back in great comfort after a good lunch. (Local food, recyclable container.) This is the harbour of Whakatane from just inside the bar. There is obviously a good deep channel and mooring buoys, but we don't know all the details of course.
The skipper told us that where we anchored off White Island there is about 10m of water. There is quite a shelf but then it drops off very fast. And to the east, less than a mile away, there is 1500 metres depth. This is the trench created by the Pacific Plate being pushed under the Australian one, the faultline which itself is feeding the volcano.