A composition of an ultrasound coupling medium is provided. The composition comprises at least 90% water, at least one preservative, and at least one base substance, wherein the composition is extensible into a film with a thickness of up to 1/10 mm, wherein the composition can withstand a pressure of up to 30 kp without tearing, wherein the composition can adapt exactly to skin surface without causing any significant air pockets, and wherein the composition can be removed from skin with substantially no residue left behind. The at least one base substance may be a galactomannan, a polyvinyl alcohol (PVA), a complex formation of galactomannan and borate ions, or comninations thereof.