A control system alters one or more characteristics of an ablating element to ablate tissue. In one aspect, the control system delivers energy nearer to the surface of the tissue by changing the frequency or power. In another aspect, the ablating element delivers focused ultrasound which is focused in at least one dimension. The ablating device may also have a number of ablating elements with different characteristics such as focal length. The invention provides an ablation apparatus and methods for ablating tissue wherein the ablation apparatus may have ablating elements that are moveable relative to the tissue to be ablated without the need to relocate the apparatus as a whole.