Disclaimer: Here are a few tips that I learned during the trips I made in Svalbard. They represent the best of my knowledge, and I hope they can be useful to someone. Under no circumstances, however, can I take any responsibility for them. If you go to Svalbard, inform yourself the best you can. Ask your guides and tour operators.
Tour
operators and guides
What
to bring and what to rent
Conditions in
summer
Equipment in
summer
Conditions in
spring
Equipment in
spring
Polar bears
It would be a bad idea to try saving money by avoiding the local tour operators. They are experienced people, who provide a whole palette of services, ranging from organised trips to tailor-made tours and logistics. Besides guide-service, they can help you in many ways: they can rent you the adequate equipment, give you important informations, and help you comply with the regulations which restrict access to certain protected areas.
You should bring with you all personal clothing, backpacks, sleeping bags, equipment such as cameras and binoculars, and skis if you plan to use them. Specialised equipment such as sledges, tents, ropes, weapons and snowscooter gear can be rent or bought in Longyearbyen. You can also buy films. If you have climbing equipment which is not too heavy for the plane, you can bring if too.
There are almost no paths, and little vegetation in the Svalbard wilderness, which can make hiking in summer more difficult than in other mountain areas. Depending on weather conditions, altitude and exposure of the place, you can encounter very different types of terrain:
One of the nice particularities of Svalbard is that there are almost no mosquitoes, and their bites don't hurt.
Basically, you should dress as for a trip in high mountains. The temperature can change a lot, with an average around 5°C. Prepare several layers, which should insulate against the wind, keep you warm, and avoid perspiration. Local people generally prefer wool, but you can also take artificial fibres if you have good experience with them. For hiking, you need good mountaineering boots and gaiters, as well as rubber boots. Boots are also comfortable when you only make a boat trip, with occasional landings. Take warm underwear, and enough pairs of socks, as well as caps and gloves. Most camping equipment is provided by the organisers, including cooking equipment and sleeping mats, but you need to bring a good sleeping bag and a thermos. Don't forget sunglasses, camera and binoculars, if you want to observe the animals. Bring along some plastic bags to take back your garbage. Remember that even paper can be conserved for a very long time in the arctic climate (I once found some newspapers from 1930 that you could still read).
The conditions in spring are very different from those in summer, since everything is frozen, which makes it easier to travel by snowscooter or skis. The temperature is usually below 0°C, and occasionally below -20°C. You should avoid narrow valleys where the snow accumulates, causing avalanches, and the regions where glaciers meet the frozen sea, where the pressure can melt the ice. When you progress on glaciers, watch the topology to avoid crevasses. Orientation can be difficult, especially in the fog. You need a compass, some people use GPS. The snow is rather dry, and not very deep in general, although the wind can accumulate it at certain places.
Basically, you need the same equipment as in summer (except rubber boots), with some extra pullovers, warm underwear, gloves and caps. For the camps, it is useful to have light warm boots. You need to melt snow every time you want to drink, so take a large thermos and a water bottle, since you need to drink frequently. When you drive snowscooters, you wear some extra gear which can be rent together with the scooters. When you ski, you should remove a pullover to avoid perspiration. I made good experiences with broad cross-country skis with a plastic sole. If you use pulks (sledges), you need skins to put below your skis. Don't try to do telemark if you have Salomon bindings, a guy in my group had some serious problems with his shoes after doing so. When you camp, put your shoes into your sleeping bag to keep them warm. Wet shirts or socks can be dried by putting them on your belly when you sleep.
Imagine for a second that you are a polar bear. You are perfectly adapted to the arctic environment, you can easily walk all kinds of grounds and swim through open water. Everything that moves can be divided into two categories: other polar bears and potential food. When you meet these funny human beings, you react according to your mood: either you just ignore them, or you get curious and take a closer look, or you are hungry and eat them.
When you make a trip in Svalbard, you should always be prepared to meet a polar bear. Stay in groups, and at least one person in the group should carry a weapon. When you camp, you cannot all go to sleep and leave the camp unattended. In summer, there is no problem taking turns to watch. In spring this is not possible in general. The solution is to build a fence around the camp, made of a wire attached to signal admunition. If a bear comes and touches the wire, it will make a lot of noise; if you're lucky, it will scare him off, otherwise, at least you will be awake. One exception: if you are dog-sledging, you don't need any watches or fences, since the dogs will warn you.