One swarm was observed to cover an area of 450 square kilometers ( 175 square miles ) of ocean , to a depth of 200 meters ( 650 feet ) .
One swarm was was estimated to contain over 2 million tons of krill .
One swarm was observed to cover an area of 450 square kilometers ( 175 square miles ) of ocean , to a depth of 200 meters ( 650 feet ) and was estimated to contain over 2 million tons of krill .