The Pacific Ocean is the largest ocean in the world at 155,557,000 sq km.   The Atlantic Ocean is the second largest ocean in the world at 76,762,000 sq km.
The cause of major depressive disorder is a combination of brain chemistry, family history, and psychosocial environment. It is not certain which of these factors dominates, but abnormal levels of the neurotransmitters norepinephrine, serotonin, and dopamine are closely linked with depression.
Depression (major depressive disorder or clinical depression) is a common but serious mood disorder. It causes severe symptoms that affect how you feel, think, and handle daily activities, such as sleeping, eating, or working. To be diagnosed with depression, the symptoms must be present for at least two weeks.