The GR20 Corsica. Paddy Dillon

September, then weekdays for the rest of the year, and are operated by Beaux Voyages, tel [phone] or 04 95 65 08 26, www.corsicar.com. Use Les Rapides Bleus Corsicatours, tel [phone], www.rapides-bleus.com, to reach Ste Lucie de Porto Vecchio for Conca, if trekking the GR20 south to north. Buses run daily from mid-June to mid-September, but not on Sundays for the rest of the year. In July and August the bus also serves Bastia airport.

      Trains run daily from Bastia to Calvi, Vizzavona and Ajaccio, tel Bastia 04 95 32 80 61, www.cf-corse.fr. A short taxi ride from the airport to nearby Casamozza might allow you to catch a bus or train that has already departed south from Bastia. If arriving by ferry to Bastia, a short walk straight inland from the ferry terminal leads to the bus terminus, behind the mairie, and railway station. Bastia tourist information office is on the Place St Nicolas, tel [phone], www.bastia-tourisme.com.

      From Ajaccio

      There are daily buses between the airport and Ajaccio, operated by TCA, tel [phone], www.bus-tca.fr. Alternatively, use a taxi to get into town – there are several operators to choose from. Those arriving by ferry berth at the Gare Routière, which is a combined ferry and bus terminal. There are no direct buses from Ajaccio to Calvi or Bastia, so it may be best to catch a train, tel Ajaccio 04 95 23 11 03, www.cf-corse.fr. The railway station is only a few minutes’ walk along the Quai l’Herminier.

      Buses serve places on the southern half of the GR20. Use Autocars Santoni, tel [phone] or 04 95 24 51 56, to reach Zicavo and Cozzano, daily in July and August, but not on Sundays through the rest of the year. Use Autocars Balesi Evasion, tel [phone], www.balesievasion.com, to reach Bavella and Porto Vecchio, daily through July and August, then only on Monday and Friday through the rest of the year. Use Alta Rocca Voyages, tel [phone], www.alta-rocca-voyages-corse.fr, to reach Bavella, daily through July and August. Use Eurocorse Voyages, tel [phone], www.eurocorse.com, to reach Porto Vecchio for onward travel to Conca, if trekking south to north, Monday to Saturday from July to mid-September. Ajaccio tourist information office is on Boulevard Roi Jérôme, tel [phone], www.ajaccio-tourisme.com.

      From Figari or Porto Vecchio

      Those who arrive at Figari airport can catch the airport bus, operated by Transports Rossi, tel [phone], or use a taxi, tel [phone], to reach Porto Vecchio. If arriving by ferry, it is a simple matter to walk into Porto Vecchio to catch a bus. Use Les Rapides Bleus Corsicatours, tel [phone], www.rapides-bleus.com, to cover the distance from Porto Vecchio to Ste Lucie de Porto Vecchio, if heading for Conca to trek the GR20 from south to north. (To reach Conca, contact the Gîte de La Tonnelle, tel [phone], www.gite-la-tonnelle.com, which operates a navette between Ste Lucie and Conca.) Stay on the bus to Bastia for onward connections by bus or train. Use Autocars Balesi Evasion, tel [phone], www.balesievasion.com, to reach Bavella and Ajaccio, daily through July and August, then only on Monday and Friday through the rest of the year. Use Eurocorse Voyages, tel [phone], www.eurocorse.com, to reach Ajaccio for onward connections by bus or train, Monday to Saturday from July to mid-September. Porto Vecchio tourist information office is on the Rue Général Leclerc, tel [phone], www.ot-portovecchio.com.

      To and from the GR20

      A handful of roads cross the GR20, and some of them offer transport links. Contact numbers for trains, buses and taxis are given at appropriate points along the course of the GR20 in this guidebook. Some nearby villages may also offer transport links, and where these are available they are noted in the guidebook. Note that there are very few buses running on Sundays, so check timetables carefully or contact the operators to confirm times and pick-up points.

When to trek

      May

      Trekking the GR20 is not recommended until at least the beginning of June, although it is sometimes possible to start in the middle of May. Last minute travel arrangements can be made if you hear that the route is clear of snow, but those who plan well in advance are taking a big chance, and deep snow could affect the higher parts of the route. The presence of snow and ice on particular parts of the route is usually mentioned on the PNRC blog, randoblogpnrc.blogspot.co.uk. An ice axe and crampons might be required, as well as the skills to use them properly.

      Trekking at this time means that the PNRC refuges, although open, will not be staffed and therefore will have no food supplies. The water supply may be disconnected and there may be no fuel on the premises. Private bergeries may be locked and bolted. It will be necessary to carry most of your food, or it may be necessary to leave the route to obtain supplies. Bus services to and from the route will be fairly limited.

      The picture on the left was taken towards the end of May and the GR20, up the gully, is heavily covered in snow; the one on the right was taken towards the end of July and the snow has gone

      June

      The PNRC refuges and private bergeries will all be fully staffed and in full operation. This used to be a quiet time to trek, but in recent years it has become very busy. The refuges will often be fully booked, and any hire tents pitched nearby might also be fully booked. Food supplies and cooked meals will be available at almost every overnight stop.

      Bear in mind that some snow and ice will still be lurking in some of the more sunless gullies, and could pose problems early in the month. Days will be warm, but not too hot. Some bus services to and from the route might not be fully operational.

      July and August

      These are the peak summer months on the GR20. Expect large numbers of trekkers and expect the refuges and hire tents to be fully booked. All services are in full swing and it is easy to obtain food and drink along the way. Bear in mind that a few seasonal water sources dry up. Should it be necessary to leave or join the route at any point, the full range of summer bus services will be available.

      This is also the hottest time of the year, with an increasing risk of afternoon thunderstorms. There have been devastating forest fires in the past around this time, closing parts of the route to trekkers.

      September

      This used to be a quiet time of year, when the numbers of trekkers reduced, but in recent years it has remained quite busy. The refuges will probably be fully booked, as may the hire tents, but as the month progresses it might be possible to stay indoors without an advance booking. Some of the bergeries offering food and drink may close, and some of the bus services to and from the route will be withdrawn. It is usual for the PNRC refuges to remain fully staffed and supplied with food to the end of the month.

      The days are cooler than the peak summer season, but remain warm and clear. After June, this is the best month to trek.

      October

      The PNRC refuges remain open, but are unstaffed and have no food supplies. While fuel might be available, it is best not to rely on it, and the water supply might be disconnected to avoid frost damage. Private bergeries will be locked and bolted, and any small food stores along the route will probably be closed, so it will be necessary to carry food, or leave the route at intervals to obtain supplies. Very few bus services will be available,