Practicalities
The Auckland day-trip question
It comes up constantly: can you see the Bay of Islands as a day trip from Auckland? By road, the honest answer is almost never. By air, it's tight but genuinely possible.
Why driving doesn't work
At 3-4 hours each way, a self-drive day trip means 6-8 hours of driving to get perhaps 3-4 hours actually at the bay — before accounting for a Hole in the Rock cruise, which alone runs 4-6 hours. The math simply doesn't leave room for the one thing most people come for.
The flight-based version
Flying into Kerikeri (about 40 minutes from Auckland) compresses the travel time enough that a very early flight up and a late flight back can realistically include a half-day cruise or a Waitangi visit — tight, and it costs you any margin for delays, but mathematically workable in a way the drive isn't.