L1157 blue-lobe outflow system. The B1 and B2 outflow cavities are indicated in red and orange, respectively. The two shock components identified through H₂O lines are displayed in blue (warm shocked gas) and in light violet for the hot tenuous gas. In the top right corner of the image we show the physical conditions of each component. The observer, represented by the Herschel satellite, is indicated on the right side of the image.