Sea ice
Because sea ice is made of frozen seawater, it is salty (unlike icebergs). Sea ice generally grows in the winter (when it is often dark all day and night) and melts in the summer (when there is twenty-four hour daylight). Sea ice normally covers more area near in the Antarctic than the Arctic. Because the ice is salty, sea ice is heavier, less transparent and easier to break than ice that isn't salty.