Compared to New Zealand's North Island, the South Island is less inhabited with much of its wilderness left untouched, leaving visitors with an overwhelming awe and wonder towards nature. It offers a spectacular range of scenery from snowy mountains to windswept beaches to quiet fiords, all of which should be slowly explored and enjoyed. The island is also famous for its focus on extreme sports and adventures, which should get your adrenaline pumping.
The South Island has plenty of natural attractions, making it a perfect destination for road trips. It is divided by the Southern Alps, which means more coastal driving with a few mountain passes and inland diversions.
New Zealand drives on the left hand side, so right-hand drivers should take extra care. Safety belts are compulsory. Some parts of the trip are in remote areas with few population centres. Stock up on food and water to be safe. Take note of your fuel usage as petrol stations may be equally sparse. Due to natural phenomena such as earthquakes, rockfalls and river washouts resulting from heavy rain, South Island highways may be blocked at times. Check for possible delays and detours from the NZ Transport Agency before setting out. Allow extra time for journeys and don't rush – the scenery more than makes up for it.
Day 1: Christchurch
Although the main attractions of the South Island lie outside its cities, Christchurch is a good place to start. The city is re-inventing itself after the 2011 earthquake, leading to exciting new urban projects. Possible day trips may be taken to Akaroa for its beautiful harbour, Hanmer Springs for its hot springs and Waipara Valley for its vineyards.
Leave early in the morning and drive 300km on the SH1/8 to Mt Cook, New Zealand's highest mountain. There are several nice walks around. Stay the night.
Day 3-4: Queenstown
Drive 250km on the SH8 to Queenstown. Go skydiving or bungee jumping - best place in New Zealand for both
Day 5-7: Milford Sound
Walk the Milford Track. If you only have a day to spend you can take the first (earlier) boat to the start of the track do an hour or so of the track then walk back and catch the later boat back.
Take the 4 day (3 nights) trek – it is really worth it (but make sure you book as far in advance as possible to avoid disappointment).
Drive through Haast Pass via Wanaka and stay in Haast. Make sure to stop for the Blue Pools Walk just north of Makarora, which features a swing bridge over the Makarora river and deep azure pools of glacial-fed water.
Day 10-13: Kaiteriteri
Drive through Buller Gorge on the way to Kaiteriteri (5hrs drive). Abel Tasman National Park; catch the boat in and walk out (1 day) or do the whole walk (2 days)- need to book well in advance. Alternatively hire kayaks and kayak into the national park, then kayak back out the next day.
Day 14: Nelson to Picton to Wellington / Blenheim to Kaikoura to Christchurch
Option 1: Nelson to Picton to Wellington
Enjoy the vineyards of Nelson before driving onwards to Picton. To finish off this South Island trip, use the ferry services from Picton to Wellington. The main services available are the Interislander  and Bluebridge Cook Strait Ferry , with the journey taking approximately 3 to 3 1/2 hours. On rough days, the ferry ride may be hard to stomach, but the first hour passing through Queen Charlotte Sound (part of the Marlborough Sounds) is more than worth the journey. Welcome the sight of Wellington Harbour set against the mountain ranges.
Option 2: Blenheim to Kaikoura to Christchurch
Drive to Blenheim. Nice vineyards on the way. And great vineyards there. Head to Kaikoura for Whale Watching (make sure you book 3-4 weeks in advance). Fish and chips on the beach. Return to Christchurch.
The roads of South Island can be windy and lonely, which may lead to accidents with the closest help several hours away. Maintain cautiousness, be sure not to drive when fatigued, and stop regularly for breaks.