The 18th data acquisition for PLP2021 took place on Tuesday 14/09/2021. Sentinel 2 multispectral data of the HDPE mesh and wooden plank mixed target, along with very high resolution images from a DJI Phantom 4 pro RTK drone were acquired. Metadata collection included wind speed and direction, light intensity and empirical measurement of turbidity using a Secchi disk. Spectrometer hyperspectral measurements were not acquired due to adverse conditions. Intense growth on the under-side of the planks and waterlogging is causing the planks to sink, consequently pulling the HDPE mesh under the water surface. Biofouling accumulation is increasing steadily on the HDPE mesh, which also contributes to the submersion of the HDPE mesh. Approximately 40% of the target is partially submerged under the sea surface, the remaining part of the target is floating on the surface, however a number of planks have sunk. Conditions windy, at approximately 4-5 Beaufort with gusts up to 6 Beaufort and waves of about 0.5 m. The sky was partially clouded over the target area during Sentinel 2 acquisition.