Devonport and North Head

This is a quaint seaside town across the harbor from downtown Auckland.  You can drive across the harbor bridge but I recommend you take the Devonport ferry from downtown ($11 return) as you get a cheap harbor cruise for free.  Once there you will arrive at Devonport wharf which has a few interesting shops and usually people fishing.  There is a nice seaside park, information centre, plenty of good cafes, art & alternative shops and a small cinema.  It is the site of New Zealand's only naval base (so don't be surprised to see plenty of navy sailors from New Zealand or other countries) and there is a navy museum for the public next to the base.  The same direction takes you to North Head, a historic gun emplacement and tunnel complex defending Auckland's harbor.  This was established in the late 1800s to defend Auckland from Russian invasion, it was then resurrected during WWII due to the imminent threat of Japanese invasion (it very nearly happened!).  Take a torch (or use the flash on your phone camera) and you can explore the impressive tunnels and gun turrets with spectacular views.  Be adventurous and follow some of the less trodden paths and tracks around the complex and you will be rewarded.  After this exercise head downhill to the sandy Cheltenham beach for a swim or suntan before heading home.
http://www.devonport.co.nz/index.htm