The Grand Couloir in Courchevel, part of the Three Valleys ski area in the French Alps, is one of the most famous black runs in the region. It is known for its steep and challenging terrain. The average gradient of the Grand Couloir is around 30 degrees, but it can reach up to approximately 38-40 degrees in some of the steeper sections. The couloir is also quite narrow in places, adding to the challenge for skiers and snowboarders. It requires advanced skiing skills and is recommended for experienced skiers due to its steepness and potential for variable snow conditions.