Black

A colour used at ski trails to indicate difficulty ratings.

In Europe

An expert slope; steep, may or may not be groomed, or may be groomed for moguls.

In North America

Black Diamond

Difficult; amongst the most difficult at a given mountain. Trails may or may not be groomed, and tend to be steep (typically 40% and up).

Double Black Diamond

Expert; very advanced ski trails that are difficult to ski and have expert terrain. They are intended only for the most experienced skiers due to their exceptionally steep slopes and other hazards such as exposure to wind, narrow trails, and the presence of obstacles such as trees or steep drop-offs.

In New Zealand

Black

More difficult than Blue.

Double Black (or Black Diamond)

More difficult than Black.

Triple Black (or Double Black Diamond)

The most difficult of all slopes - dubbed 'suicidal' by some resorts.

In Japan

Expert slopes; the steepest and most difficult slopes at the ski area.