Satellite observation (GEOS-12) of Hurricane Katrina in August 2005 in the Gulf of Mexico - Source : NASA-NOAA
Rosette used to collect seawater samples during a scientific cruise in the South Pacific Ocean. Duringthe austral summer,the amount of chlorophyllais so low thatthe water becomesdeepblue,almostpurple. (Photo : Joséphine Ras)