The Kora is moderately to highly challenging. It covers about $52$ kilometers (or $32$ miles) and takes pilgrims to a high altitude, including crossing the Drolma La Pass at $5,630$ meters. The difficulty stems primarily from the high elevation and the unpredictable weather, requiring excellent physical fitness and proper acclimatization.

There are typically two main routes:

1. Via Kathmandu, Nepal: This involves flying to Nepalgunj or a similar entry point and then driving/flying across the border into Tibet (China).

2. Via Lhasa, Tibet (China): This route involves flying to Lhasa and then undertaking a longer drive across the Tibetan Plateau to reach the holy sites.

3. The Lipulekh Pass Route (through Uttarakhand, India): This is a traditional, challenging trekking route managed by the Indian government (currently undergoing infrastructure development).

Yes, altitude sickness (AMS) is the most significant risk. The journey remains at very high altitudes, with stops around $4,000$ to $5,000$ meters. It is essential to include adequate acclimatization days, ascend slowly, stay hydrated, and consult a physician about preventive medication before the trip.

As the holy sites are in the Tibetan Autonomous Region of China, you will need a valid passport and a Chinese Visa/Tibet Travel Permit (often handled by the tour operator as a group permit) to enter the region. Specific permits may also be required depending on the chosen route.