"first-year sea ice" is ice that is thicker than "young ice" but has no more than one year growth. in other words, it is ice that grows in the fall and winter (after it has gone through the "new ice – nilas – young ice" stages and grows further) but does not survive the spring and summer months (it melts away). the thickness of this ice typically ranges from to . first-year ice may be further divided into "thin" ( to ), "medium" ( to ) and "thick" (>).