My personal recommendation is to walk to the summit yourself if you possibly can. If you are moderately fit and able it is an easy walk, taking around 2 hours to complete the round trip (longer, of course, if you explore, take photos, and generally take your time). Fairly new boardwalks make the previously difficult lava fields a breeze. However, for those who would find the going difficult, or who have young children with them, the tractor-pulled train will take you almost to the summit, leaving just a short stretch of boardwalk to the very top.
You can arrange this as part of your ferry ticket price. It is certainly a popular option, so can be busy during holiday periods.
Incidentally, the crater rim at the top of Rangitoto has a narrow, unmade path around it's edge. It is quite safe, and an easy, short side trip worth taking while you are at the top.
I am very fortunate - some friends dropped me off at Rangitoto from their boat and picked me up later after I had climbed it and they had enjoyed a days fishing. However, you can get there just as easily via the local Fullers Ferry. From the Downtown Auckland ferry terminal, it takes about half an hour to reach Rangitoto, or you can also get here from some of the more outlying marinas, such as Half Moon Bay, Waiheke Island and Pine Harbour.
Let's assume you will come from Auckland. The Fullers Ferry departs regularly and offers you the option of either a basic return fare, or a guided tour including a tractor-pulled ride up the slopes to just below the summit (see next tip). The basic return fare is $20 per adult, with open same-day return times, and the guided island tour package is a heftier $50 per adult.
The Fullers website below will give you ferry departure times.
Ferries connect the volcanic island of Rangitoto with downtown Auckland several times each day.
I caught one of these ferries, operated by "Fullers", for a day-trip during my visit to Auckland in March 2006. The following information is correct as of that date:
Ferries to Rangitoto depart from Auckland's ferry building daily at 9:15am, 12:15pm and 3pm. They return to Auckland at 9:45am, 12:45pm and 3:30pm. There is an additional ferry from Rangitoto to Auckland at 5pm on weekends.
The journey between Auckland and Rangitoto takes approximately 30 minutes (via a short stop to pick-up passengers at Devonport).
Adults: 18.40 NZD return
Children: 10.40 NZD return
As Rangitoto is practically uninhabited and there is nowhere on the island to purchase tickets, you must purchase a return ticket at Auckland.
There are a number of private ferries who run trips to Rangitoto Wharf . You can either ‘ do it yourself’ and just take the ferry ride (around NZ$20 – family tickets are also available), or you can book a tour which includes a tour of the island as well. Ferry’s depart from Devonport Wharf and the Ferry Terminal in Quay St, downtown Auckland.