ETHICAL ISSUES: The International Campaign for Tibet discusses ethical issues related to Tibetan travel at www.savetibet.org/tibet/travel/index.php.

DOCUMENTATION: Foreigners must obtain a visa to visit China as well as an additional permit for visiting Tibet. A number of travel agencies outside China offer packaged tours that include train tickets and the necessary permits. Web sites with information include

www.lonelyplanet.com/travelstories/article/tibetfaq_0707; or

en.tibettour.com.cn/. The China National Tourist Office — www.cnto.org or 888-760-8218 — can help locate a tour operator to arrange the trip.

TRAIN TO TIBET: The Beijing-Lhasa trip takes about 48 hours. One-way tickets range from about $50 for a seat to $170 for a bunk in a four-bed cabin. Tickets can be harder to obtain heading into Lhasa than leaving Lhasa, especially in peak summer season; as a result, some travelers fly to Lhasa and take the train back.

TIPS:

— Lhasa is located at about 12,000 feet, or more than two miles, above sea level. Altitude sickness is common among visitors. Some hotels sell oxygen and have doctors on call. Tourists are advised to bring extra water and high energy snacks, along with basic medications for headache, diarrhea and minor ailments.

— The disk drives of some laptop computers and other portable electronic devices may crash at high altitudes and data could be lost.