Among other disclosed subject matter, a lighting device cooled by being at least partially submerged is provided. The lighting device includes a housing forming a chamber having at least one transparent portion. The lighting device includes a diode in the chamber emitting light through the transparent portion. The lighting device includes a cooling conduit configured for a liquid to flow along the chamber when the lighting device is at least partially submerged in the liquid, without the liquid contacting the diode. The diode is mounted on a surface that abuts the cooling conduit.