Surface representation of the L1689B Herschel PACS map at 160 μm amplifying the substructure. The main filament axis is rotated horizontally and the core is in the center. Two narrow filaments are visible on the right perpendicular to the main filament, and the filament shows a narrow substructure along the main filament axis west of the core. There is also sub-structure visible in the central core region at this wavelength.