Another Holy War could be fought out about stoves. The refuges offer usage of their gas stoves for 10 FF (if you stay the night, the gas is inclusive), so you probably won't need one. But if you don't want to sleep in the refuges (and there are several good reasons for this) or you just wish to save money (buy food in the supermarkets and cook your own meals) you should have one.
It's a matter of taste which type of fuel you choose. At the coast and in the towns, every kind of camping fuel is available, but if you are in remote regions, the only kind of fuel you'll find is the Bleuet 206 Camping-gaz cartridge. Methylated spirits is only available in supermarkets, but this fuel is light and compact, so you should be able to carry enough with you. My personal choice is methylated spirits; it's ecologically beneficial, you don't have to throw away cartridges every day or the other, and the stove of my choice burns it. You should use a leakproof fuel bottle; alcool tends to leak through every small chink.
This leads us again to the stove question. In contrary to many other areas, you don't need a windproof stove on Corsica; there's enough stuff lying round to build a small windshield if you need one. A simple gas stove with Bleuet 206 cartridges will do fine, and most people we met used one. I have a Trangia stove that contains all the things you need (burner, windscreen, two pots, a frying pan/cover, a grip and a kettle), weighs about 1.35kg, has a diameter of about 22cm (8.7") and is about 11cm (4.3") high. This stove is unbeatable in heavy winds, and it's not inferior to a normal gas stove in any way.
We took 1 liter of methylated spirits with us, and that sufficed for about 10 days (half way the GR 20). If you use the refuge gas as often as possible, 1 liter of spirit is definitely enough (just for your convenience; you don't have to eat in the refuge if it's overcrowded).
A waterproof lighter is not important on Corsica. But make sure you have several lighters placed all over your equipment to make sure you find one if you need it, even if you lose one.
If you go to remote places you should have a medicine kit. These were
the contents of ours:
I hope I didn't write complete crap... my teacher never taught me such
words (English is not my native language). One useful thing we forgot is a
medicament against a sore throat. But remember: everything you take with you
is useless if you don't know how to use it. Make sure you know.
Don't forget cork-screw and tin-opener!
Take enough toilet paper with you. It's a very useful stuff, and you can't buy single rolls. Stow it away in a bag (waterproof)! You normally won't find toilet paper in refuges or on camping sites.
If you cook your own meals, don't forget spices, especially salt and pepper. You'll need lots of salt when cooking rice and noodles. Tea and vitamine pop taste better than water, so don't forget such things.
Of course you are going to take a camera with you. It needn't be a heavy reflex camera, but a "pocket" isn't the right thing, too. Use films for slides, ISO 100 will do; buy them at home, they are much cheaper there! Don't forget a spare battery for the camera!
As I already said, rain is fairly rare in Summer on Corsica. Nevertheless you should have a light raincoat and some sort of cover for your rucksack. You won't need a rain poncho for Corsica, though. We've met people who did the northern part of the GR 20 who told us about a heavy rain during a thunderstorm, but we didn't have to use our rain protection. Wrap everything inside your rucksack into plastic bags; it's not only useful, it also protects them from rain. Don't even consider taking an umbrella with you, it's worthless.
Sleeping-bag: if you just stay at the coast, you won't need one; a
cover is sufficient. But if you go hiking in the mountains, it's
indispensable: the nights can be pretty cold (8°C/46°F and less), and
outside the refuges that's damn cold without a sleeping-bag. It doesn't
matter which kind of sleeping-bag you have (on Corsica!), if it's just
warm enough and not too heavy. Make sure you stow away your
sleeping-bag in a rainproof place!
An insulation mat is a must have. It just has to be not too thin and
not spongy, make sure it doesn't soak up water! Good mats need not be
expensive; you should be able to buy them for about 15 US$. Insulation
mats are often pretty short (185 cm, or 6'1"), but that's not a
problem (even if you are taller; all three of us are), because you
don't need the mat under your head if you sleep in a tent (there's the
pillow). Better turn up the mat at your feet to protect your bag from getting
wet with condensing water from the tent.
If you already have telescope sticks, take them with you, they are useful. We had none, and it worked, too.
You won't need many clothes. A pair of jeans is the most useless item
you can carry with you: too heavy, too warm, and soaks up too much
water. On most days, shorts (two pairs) are best, and for the evenings
and mornings in the mountains, a light pair of cloth trousers is fine.
Add three or four T-shirts, some briefs, some pairs of
socks (or one pair of socks and two pairs of stockings if you
are hiking the mountains), and you're done. In the mountains, you might want
to have a T-shirt with long sleeves for the mornings and evenings. A light
but warm jacket or a pullover is also useful - remember, the
nights can be lousy cold, and the evenings and mornings can be fresh, too.
What you need for hygiene is left to you, but think about every little item! Everything has its weight! Some things you might forget: a pair of scissors for the nails, Q-tips, and plugs for the ears. Believe me, every refuge has its snorers! If you have sensitive skin, you might need an after-shave (of course filled in a little plastic bottle), but try at home if you can live without it.
How to shave? Don't bother carrying an electrical shaver, use one of
those cheap and light razors with removable blade heads. Take enough
blades with you, they become blunt real fast when they can't dry out on
the shelf. Shaving-cream belongs to the group equipment; don't try to
shave without, it can result in a torture.
Don't forget sun lotion! Which protection factor you should use depends on what you are going to do and what your skin needs. If you stay in the mountains, 8-12 should do even for sensitives, but if you want to grill on the beach the whole day this probably won't be enough in the first days. Hikers, don't forget the back of the neck and the shoulders (the most exposed part of the body, even if you wear a T-shirt!) and the feet (the part that's most unused to sun radiation) when bathing.
Not only important for hitchhikers to the galaxy (especially cool froods) but also for you: a towel, not too big, not too small, and not mommy's best.
If you wear glasses (and everybody should at least wear sunglasses there), you should have a hard case and a cleaning cloth. Remove fat stains with rinsing agent, water and toilet paper. A small screwdriver for the bow screws may be a good thing to have.
Don't forget a sun-hat if you're a hiker! Brighter colors don't absorb that much radiation, and a cloth hat can be kept wet more easily than a straw hat, but both will do. Try to cover the back of your neck, or use lots of sun lotion there. Or a hanky and safety pins!
Take a flashlight with you. The smaller and lighter, the better, but it should also be robust, bright and, if possible, waterproof. These small aluminium sticks for two mignon cells (Maglite AA or imitation) are a good compromise. Take only as many batteries with you as you will need. Two complete sets of batteries are fully sufficient for two weeks, and if you are in a group with several flashlights, one set is enough. Use alkaline batteries, they have a better energy to weight ratio. Don't forget a spare bulb!
Of course you can't do without cutlery. Knife, fork and spoon in a set (or out of the drawer with an elastic band), a soup plate made of plastic or aluminium and a cup (plastic or stainless steel). Remember, the one with be biggest plate and the biggest cup gets most of the soup and the tea...
Make sure you have one sharp knife in your group. One will do! You'll need it for the Corsean salami.
One or two water bottles with a total of at least 2 liters. If you
don't want to spend much money, take two of those polyethylene bottles
beverages often come in and put them inside your insulation mat
(that'll keep them cool and safe). If you decide to take aluminium
bottles, use those coated with plastic inside.
Paper and ball-pens, not only for the Usenet travelogue. There's always something to write down, eg. train departures.
Since you already got to this chapter I assume you are a frequent
reader. Take a thick book with you, it really makes a difference if you
stare holes in the walls or not when waiting for a train or a bus. Of
course a book takes its space and has its weight, but all the other
useless things you have with you do that, too.
As a real professional, you take some meters of strong, thin cord with you (ask a kiter which one is best...). It is not only a clothes-line, it serves also as emergency shoe-lace. You recognize the pros for the clothespins they have with them and that protect their clothes from falling into the mud when the wind blows.
Further details see Appendix I.