Your ball is in a bunker when any part of it touches sand on the ground inside the edge of the bunker.Your ball is also in a bunker if it is inside the edge of the bunker and rests:
On ground where sand would normally be, or
In or on a loose impediment, movable obstruction, abnormal course condition or integral object in the bunker.
If your ball lies on soil or grass or other growing or attached natural objects inside the edge of the bunker without touching sand, your ball is not in the bunker.
DIAGRAM 12.1: WHEN BALL IS IN BUNKER
In line with the definition of bunker and Rule 12.1, the diagram provides examples of when a ball is in and not in a bunker.