The Franz Josef is a 12 km (7.5 mi) long glacier located in Westland Tai Poutini National Park on the West Coast of New Zealand's South Island. Together with the Fox Glacier 20 km (12 mi) to the south, it is unique in descending from the Southern Alps to less than 300 metres (980 ft) above sea level, amidst the greenery and lushness of a temperate rainforest.
Having retreated several kilometres between the 1940s and 1980s, the glacier entered an advancing phase in 1984 and at times has advanced at the phenomenal rate of 70 cm a day. The flow rate is about 10 times that of typical glaciers. Over the longer term, the glacier has retreated since the last ice age, and it is believed that it extended into the sea some 10,000 to 15,000 years ago.
The glacier area is one of the main tourist attractions of the West Coast, with around 250,000 visitors a year, and up to 2,700 per day. Guided and unguided walks up to and onto the glacier are possible. However, since April 2012 all glacier walks require a helicopter flight past the unstable terminal face,; glacier walks also require some specialised equipment, namely ice axes and crampons that latch onto a sturdy boot.
As the walking part of any tour up to the glacier takes a long time, and ends at the first icefall (a frozen waterfall, draping a natural step in the land underneath), numerous tourists book helicopter tours from one of the several local airlines, which usually drop their guests between the first and second icefalls, for a guided 1-2 hour walk through the broken ground atop the glacier.
Franz Josef township is a little service village (approximately 330 inhabitants) located approximately 5 km away from the face of the glacier on State Highway 6. It has a small but busy heliport, numerous tourist accommodation options (with up to 2,000 people staying overnight during the main season) and a number of restaurants and shops.
The glacier was still advancing until 2008, but since then it has entered a very rapid phase of retreat. As is the case for most other New Zealand glaciers which are mainly found on the eastern side of the southern alps, the shrinking process is attributed to global warming.