English: Fiberglass submersible built and used by colombian drug smuglers. Because much of its structure is made of fiberglass and it travels mainly below the water surface, it is virtually impossible to detect via sonar or radar. en:Narco submarines also have an upper lead shielding to minimize their heat signature to throw off infrared sensors. In most cases, this means visually spotting them from the air, although they are also painted blue or green and produce only little wake.