On the next day, the multitude that stood on the other side of the sea saw that there was no other boat there, except the one in which his disciples had embarked, and that Jesus hadn't entered with his disciples into the boat, but his disciples had gone away alone.
Why did John bother to relate this seemingly unimportant information? Apparently he did so to document the fact that Jesus really had crossed the lake by walking on the water. Another reason could be that his description supports Jesus’ statement that the people sought Him (John 6:26). In view of what these people proceeded to demand of Jesus (John 6:30-31) it was important that John show that they were the very people who had witnessed the sign of the miraculous feeding.