What is the best activity to do in New Zealand as a Traveller and what would people reccomend to see and do?

There is really too much to list - you'll find something amazing no matter where you go.

The 'classic' tourist spots would be:

North Is:
Cape Reinga/Ninety Mile Beach
Bay of Islands
Auckland
Coromandel Pennisula
Waihi
Waitomo Caves
White Is/Whakatane
Lake Taupo
Mt. Ruapehu
Rotorua
Napier
Mt. Taranaki/New Plymouth
Whirinaki National Forest
Wellington

South Is:
Nelson
Marlborough
Kaikoura
Arthurs Pass National Park
Aoraki (Mt Cook) National Park
Moraki Boulders
Franz Josef Glacier
Milford Sound
Doubtful Sound
Fiordland National Park
Chatam Islands
Dunedin
Queenstown
Christchurch

It all depends how you want to bias your experience.

Use tools available to you on these sites:
http://www.newzealand.com/travel/
http://www.aaguides.co.nz/main/index.sht...
http://www.airnewzealand.co.nz/default.h...

To follow on from the previous answerer, if you are staying in/around Auckland - here are some recomendations:

* Auckland War Memorial Museum
* Museum of Transport and Technology (MOTAT)
* Mt Eden and the view from the top
* Cornwall Park (One Tree Hill)
* A rugby game at Eden park if visting in rugby season
* A ferry ride and hike up Rangitoto Island
* A harbour cruise on the Waitemata
* Shopping on Queen St.
* Take a ferry or plane to Waiheke Island and take in the artsy alternative lifestyle many islanders lead.
* The red light district of K road.
* Piha or other west coast black sand beaches.
* A day/weekend trip to the Coromandel Pennisula.
* Hiking in the Waitakere Ranges
* Kelly Tarlton's Underwater World
* The Sky Tower
* A tea or coffee at a street table in old Parnell.
* visit some wineries in west Auckland
* A day at the beach at Mission Bay or surrounds
* Check out some of the history at the America's Cup Viaduct
* A ferry trip to Devonport


Also - If you are a member of the AAA in the USA or some other qualifying automobile association around the world, you can sign up with a sister-relationship membership with the AA in New Zealand ahead of your trip and have them send you their travel quides and maps and you are also then eligible for discounted car rental rates, discounted accomodation rates and discounted rates at many sight seeing activities. See:
http://www.aa.co.nz/Section?Action=View&...

I grew up in New Zealand and have lived in two other countries yet, whenever I meet someone who says they took a trip to NZ they ALWAYS say how much they loved it. You will too.

I gather you're flying into Auckland. One of the easiest things to do and enjoy for all ages is a ferry ride (30 mins) to Waiheke Island and a tour of the wineries, local artists village and enjoy the breathtaking views! You might even go for a sail once you get there. It's a great day trip or a romantic overnight! Very economical and not physically taxing.

Happy Travels.

I suggest one place you MUST try to include is Queenstown, in the lower central South Island.
Incredibly beautiful scenery, and heaps of activities: jetboating, bungee jumping (the world's "home" and origin of this!), paragliging, skyline gondola, etc
The town itself is a tourist heaven (NZ-style ;-)) - and the southern part of the country generally has the spectacular scenery.
(North Island has 80% of the population - South Island has 80% of the scenery <lol>)

Milford Sound is also worth a visit, though even more "distant" than Queenstown.

Also perhaps Rotorua (central North Island) would be good place to experience some Maori (native) culture, as well as volcanic activity like boiling mud pools, geysers, etc (I believe only 3 countries in the world have geysers: USA, Iceland, New Zealand).

Enjoy your trip :-))

P.S. The photo of me you see was taken at Stewart Island - a most WONDERFUL place to really get away from it all for 2 or 3 days - unspoiled native bush, flora and fauna, sea and sky, bush walks everywhere, and only very few people in the tiny community on one corner (though 4 or 5 backpackers' hostels, hotels, etc.)