Active Sonar Map
The Active Sonar Map is a new gear item introduced in Tomb Raider Underworld. It emits a sonar ping to create a 3D image of Lara's surroundings, thus making it perfect for uncovering hidden items and locations.
To access it the player must access Lara's PDA system and select the sonar. This then triggers the sonar ping, then shortly after a three dimensional image of the area the ping has travelled is seen. The sonar cannot create an image of something which is hidden behind something else, for example if the player is standing behind a pillar in a relatively empty room and activates the sonar, a 3D image of the room in front of the pillar would not be created. This can easily be over come by moving to a more accessible spot. After the sonar is activated the 3D image of the surroundings stay a part of the image regardless to how many times you use it, only adding more to the image. This only stays in effect when the player is in the same level, once you have moved to another level the image will be erased and a new one must be created.