When it was evening, his disciples went down to the sea, embarked in a boat, and went across the sea to Capernaum. It had already grown dark, and Jesus had not yet come to them. The sea was stirred up because a strong wind was blowing. When they had rowed about three or four miles, they saw Jesus walking on the sea and coming near the boat, and they began to be afraid. But he said to them, "It is I. Do not be afraid." They wanted to take him into the boat, but the boat immediately arrived at the shore to which they were heading. (Jn 6:16-21)
This chapter of John’s gospel takes place in the context of exodus and particularly of Passover. So we are obliged to read this event of walking on the water also on the background of exodus. Israelites started their life of freedom by coming through the Red Sea. Moses parted the Red Sea and led them to the wilderness while they were chased by their pursuers.
Here in this story the crowd has just declared Jesus to be the prophet who has come into this world. The prophet, that is like Moses. Sea, in general, was chaos for the Jews. It was evil and an untameable force. They always celebrated God as the king over mighty waters. The fishermen also were afraid of the Sea of Galilee. This sea would suddenly become rough and frightening.
Except Luke, the three gospel writers place this event of walking on the water just after the feeding of the five thousand. The disciples see him walking on the water and the crowd sees him and are surprised to see him (Rabbi when did you come here). Jesus said to the disciples;’ It is I. Do not be afraid’. This reminds them of Gods presence among them as in the case of Exodus. As he is there with them then they are on the shore of Capernaum. He led them to the other side of the sea.