The altitude of sea level is recorded as 0 m, and the altitude is + 450 m, indicating______ The altitude is - 102 m, which means______ .

The altitude of sea level is recorded as 0 m, and the altitude is + 450 m, indicating______ The altitude is - 102 m, which means______ .

An altitude of + 450m means 450m above sea level, and an altitude of - 102m means 102m below sea level