Abstract: A trolling device for fishing at a desired depth comprises a plate-like hydrofoil member having a leading edge and a trailing edge, a first strut extending upwardly from the hydrofoil member, the strut having an opening or other securing device for securing it to the end of a downrigger line to tow the device behind a boat. A releasable fastening device is secured to the trolling device for releasably securing it to an intermediate position on a fishing line. A weighted keel assembly depends downwardly from the hydrofoil member to direct it downwardly at its leading edge into a diving position when the device is suspended from the towing or downrigger line of a boat.