Blindness - External Darkness

Compared to other senses, eyes are the main medium of understanding of the external environment. Has anyone closed their eyes for an hour and tried to do their regular activities? It is really amazing. I just closed my eyes and stayed in one place, trying to hear, feel and sense the environment around me, I was so shocked to note, that humans depend total on eyes for understanding the environment around us. I began to wonder, How blind people manage to cope up with the life?