The opening word from the Hebrew text of Micah 7:19: "and thou wilt cast all their sins into the depths of the sea." Based on the imagery of this verse, it is customary in many Jewish communities to observe the Tashlikh ceremony, in which people go to a body of water on the afternoon of Rosh Hashanah and symbolically throw their sins into the water.
Tashlikh (Hebrew, meaning "casting off") is a long-standing practice on Rosh Hashanah (the Jewish new year according to the Hebrew calendar) to go to a large, natural body of flowing water (such as a river, lake, sea or ocean) and throw some bread, or a similar food item, into the water, symbolically casting off the sins of the previous year.