[en] We report new submillimeter (effective wavelength approx.400 μ) observations of three dense molecular clouds: NGC 2024 (Orion B) OMC-2 (in Orion A) and Mon R-2. These objects strongly resemble the far-infrared source in the Kleinmann-Low nebula in Orion A. An extensive map of NGC 2024 shows the peak of submillimeter brightness to coincide with the peak locations of far-infrared (approx.100 μ) continuum and HCN molecular-line emissions. The submillimeter and far-infrared brightness distributions differ in spatial detail, suggesting that the submillimeter emission comes from a cool region with temperature approx.25 K (inferred from the surface brightness of the optically thick ¹²C¹⁶O line). Arguments based upon the column density derived from optically thin molecular lines yield an effective mass-absorption coefficient of 17 cm² gm^-1 for the continuum opacity at 400 μ; however, this estimate is subject to large uncertainties.We suggest that the star 2024 No. 2 is imbedded in the molecular cloud and supplies the energy of the submillimeter emission