Marine Day on Zushi Beach, and amu's founder walks you from a beach cleanup into the science of what washes ashore. You sort real ocean plastic by density, hear how retired fishing nets are turned back into material, and take home a carabiner made from the haul. The fieldwork runs from 9am; a Hawaiian barbecue at the beach house follows. Entry is 8,800 yen, or 5,500 for store buyers, with the barbecue a further 7,000 yen. Come by train.