See NewZealand.com's Key Facts and FourCorners.co.nz New Zealand Facts for general visitor information about language, driving, time differences and so forth. Information below is tramping-specific.

Climate

Seasons are reversed compared with the northern hemisphere, so summer is December-February and winter is June-August. The north of the North Island is warmest, while the south of the South Island is coolest. Temperatures are typically 5-15 degrees Celsius in winter and 10-25 degrees Celsius in summer. In the mountains, rain and snow can be expected at any time of year. Weather conditions are highly changeable and unpredictable. You should always pack rainwear and layers of thermal clothing that can be worn or removed as required. Mid-summer tramping can be very hot, even in the mountains. Autumn and Spring are probably the most pleasant seasons for tramping.

Animals

New Zealand is a land of birds. Historically, the only land mammals were a few bats. Many birds became flightless. New Zealand inherited a bizarre variety of birds. Today, introduced cats, dogs, stoats and rats pose a grave threat to New Zealand bird species with many having already become extinct. There are few potentially dangerous animals in New Zealand.

Geography

New Zealand is a chain of three main islands about the size of the United Kingdom or Japan. From north to south, these islands are known as the North Island, the South Island and Stewart Island or Rakiura. The national population is just over 4 million people.

North Island

Most people live in the north of the North Island around Auckland. The national capital is Wellington, at the bottom of the North Island. This island is dominated by farmland, but features a distinctive "volcanic plateau" at its heart. This area includes the Ruapehu, Tongariro, and Ngauruhoe volcanoes (strictly speaking, Ngauruhoe is an active cone of the Tongariro Volcano). The massive lake at the centre of the North Island, Taupo, is actually another massive volcano. It last erupted in 182AD, causing great devastation. Mount Egmont / Taranaki is another striking volcano to the southwest.

South Island

The South Island is dominated by the Southern Alps, a young mountain range that runs most of the length of the island. This range includes New Zealand's highest mountain, Aoraki / Mount Cook (3754m). There are two key cities in the South Island: Christchurch about midway down the east coast and Dunedin near the bottom of the east coast. The town of Queenstown, inland from Dunedin, is also a good base for outdoor adventure.

While lacking the spectacular volcanism of the North Island, the South Island offers the most variety for trampers. The West Coast is relatively wet and rainy, creating rich, diverse, tangled forests, compared with drier beech forests to the east. The southwest corner of the island is dominated by glacier-carved valleys and is particularly wet and inaccessible. Many of the most famous tracks are in this area, including the Routeburn, Milford and Kepler Tracks. The northern tip of the island offers palm beaches, karst landscapes, and ancient grassland peneplains.

There are three passes over the Southern Alps. Each offers a variety of tramping tracks and routes. Furthest south is Haast Pass which leads from near Wanaka through to the West Coast. Tracks in this area are mostly challenging wilderness experiences. Further north is the raw landscape of Arthur's Pass. Arthur's Pass National Park contains a large selection of tracks, mostly maintained to a basic level. Being just a few hours from Christchurch, the park is a good landscape for competent tramping parties to explore. Further north still is Lewis Pass, a beautiful drive through tall beech forests. There are many easier tracks in this area as well as some easier "tops" routes.

Public land

New Zealand has 13 national parks, each preserving outstanding and distinctive landscapes. Tongariro was our first national park and is also a World Heritage Area. In the southwest of the South Island, Fiordland, Mount Aspiring, Westland, and Aoraki/Mount Cook National Parks combine to form another World Heritage Area. Entry to national parks is free and uncontrolled. Many activities are prohibited in national parks such as off-road vehicles (including mountain bikes) and unlicenced commercial activities (including guiding parties).

Supplementing the national parks are a variety of other reserves, grasslands parks, and forest parks. These areas are often less tightly controlled (horse trekking and mountain biking may be allowed, for example) and may be less distinctive. Most areas a freely accessible.

Public lands are managed by the Department of Conservation (DOC). DOC visitor centres are found throughout the country in towns and national parks. DOC can provide information and advice on tracks, weather, and current conditions.   

New Zealand has a well-established system of basic backcountry huts available for public use and administered by DOC. Most of these are available on a first-come first served basis, although hut users must be prepared to share with all later arrivals. Most huts cannot be booked, although you are expected to pay for use in advance.

Safety

Rivers

As there is such a short distance between mountains and sea, Rivers in New Zealand rise quickly during rain and can become impassable. Fortunately, they also fall quickly so be prepared to wait it out. The best river crossing technique is to form a line of people with the strongest person upstream, place your arms between your neighbours' backs and packs and grab the straps on the far side. As a chain, aim to cross diagonally downstram, moving with the current. If you cannot see the bottom or if you feel rocks moving past your feet, retreat back to the river bank. So many people have died on drowning in New Zealand rivers that it was known as "the New Zealand Death" in colonial times.

Hypothermia

Hypothermia is another serious hazard. It occurs when your core body temperature (as opposed to your fingers and toes) drops. It can be caused by exhaustion, getting wet, and having inadequate warm clothing. Symptoms include sluggishness and confusion. The victim may not complain of feeling cold and may not shiver. If you are cold, you should not push on because you are "almost there". You should change your clothing (borrow some if necessary). A woollen hat is critical, and a raincoat can help by stopping wind. If you think a party member is hypothermic, your group must deal with that before attempting to continue to your destination. Ensure the person is not wet and is well wrapped up and give them carbohydrate-rich food. If they appear to be severely hypothermic, plan to camp on the spot. The classic treatment is two people in one sleeping bag. Body warmth is the best way of warming someone gently. Do not give hot drinks. If you are trapped in rain, packs, pack liners and survival bags can be used to keep the rain off. Remember that down sleeping bags are ineffective if wet.

Getting lost

If you become separated from your party and lost, the best thing to do is stop moving. They will come to find you but won't be able to if you move around. Set up a camp and keep yourself warm. Search and rescue operations divide landscape up into a grid and work through it systematically. Once again, if you move around they may not find you. Before setting out, always fill out intentions forms in DOC visitor centres and leave notes in hut books even if you do not stay in the hut. Remember to cancel your intentions forms when you return.

Wildlife

There are no bears, snakes, scorpions, or major spiders to content with. There is one poisonous spider called the katipo, but it inhabits unaltered sand dune areas and is very rare. Seals and sea lions can bve found around the coastline and can become aggressive if cornered. In particular, sea lions are not afraid of humans and will chase you if you approach them too closely. Generally, keep a distance of 10 metres. Falcons are becoming more common in forested river landscapes. They will dive at you if you inadvertantly approach their nest. If you do not keep your head down they may strike it. Generally, all native wildlife in New Zealand is protected and may not be harmed or interfered with.  

One notable animal is the sandfly, a small black biting fly. It does not carry disease but it inflicts an annoying bite. Insect repellant is essential in some areas, particularly the West Coast of the South Island. Sandflies are active during daylight, and particularly around wet, grassy areas on overcast days. Sandflies will not bother you while you are tramping as they cannot catch you, but they will find you as soon as you stop! You won't encounter many mosquitoes in New Zealand, and they do not carry disease.

Water

Giardia is a nasty disease that has been detected in some New Zealand rivers. However, reports of people suffering from Giardia seem to be very rare. A general rule is that water in side-creeks draining forested hillsides should be fine. Remember you are far more likely to suffer symptoms due to dehydration than due to water-borne diseases. It is generally not necessary to filter or treat water, but you may like to do so.

Note that putting your head under water in a thermal pool anywhere carries an exceedingly slim chance of amoebic meningitis, a deadly disease. If you do this by accident, blow your nose firmly and thoroughly.

Finally...

Visitors to New Zealand often underestimate the ruggedness of the landscape and the variability of the weather with fatal consequences. Easy routes and river crossings can become dangerous or impossible in hours. Take a map and know how to read it. Be prepared to change your plans. Take spare clothing and a raincoat with you even on short walks.