Waiheke Island is the most populated island in the Hauraki Gulf, and is located about 12 miles (20 kms) from downtown Auckland. It's easy to get there by ferry from Auckland, as well as charter airplane or helicopter.
Many ferries run between Auckland and Waiheke Island every day. As many residents of Waiheke commute to Auckland for work, the ferry services are not simply put on for tourists. Ferries depart from the Auckland City Ferry Terminal on Quay Street, as well as from Half Moon Bay in north-east Auckland, and from Devonport on the North Shore. The first ferries leave early in the morning, before 6am, and the last ones after midnight. The fastest ferries take around 40 minutes, whereas some take up to 90 minutes. Most ferries arrive at the main port on Waiheke Island, Matiatia Wharf, but some go to Orapiu Wharf and Kennedy Point. Most ferry services are passenger only, but there are also limited car ferry services.
It's also possible to charter a private boat to take you to Waiheke.
To get to Waiheke Island by air it's necessary to charter a fixed-wing aircraft, seaplane or helicopter. Waiheke can be included in a private sightseeing tour of the Auckland region by air. This is much more expensive than getting the ferry, but you can get a customized experience and the views are beautiful.