System) is used to index megafauna and plastic litter on the Arctic sea floor. ROV To observe the sea-ice system from below, this under ice remotely operated vehicle (ROV) combines an off the shelf modules [...] mammals like whales and walruses. Ice Mass balance Buoy Like a tentacle in snow and ice, a thermistor chain measures air temperature, snow depth, ice thickness, and snow, ice and water temperature. [...] sinking velocities at high temporal resolution. Winch system Due to ice coverage and rough seas, profiling the upper water column in Polar Seas year round is a serious challenge. The AWI winch system SWIPS has