While the crowd was pressing in on Jesus and listening to the word of God, he was standing by the Lake of Gennesaret. He saw two boats there alongside the lake; the fishermen had disembarked and were washing their nets. Getting into one of the boats, the one belonging to Simon, he asked him to put out a short distance from the shore. Then he sat down and taught the crowds from the boat. (Lk 5,1-3)
The crowd was pressing in on Jesus to listen to the word of God.
But the word of God was read and preached in the synagogue. Jews had such a respect for the word of God that they would not play about with it. Especially they would not look for it in the sea shore/lakeside. So the crowd was more on to Jesus and the words of the Kingdom that he was preaching. The word of (God) Jesus was attracting the crowd.
Why do we find the preacher on the sea shore or the lakeside?
So he himself was not like the official preachers who were found in the temple and in the synagogues or in their homes. Sea shore/lakeside is the place where you find no buildings, no structures, and no institutions. It is an open space. Only the elements of nature like air, water, earth, space and fire (to cook fish) are found. Basic created elements are there and visible and observable. Probably Jesus wanted to preach to the universe and the people were also a part of these listeners.
If you know the geography of the people of Israel, then you will understand that sea is the farthest end of the earth and there is nothing beyond. So Jesus takes the extreme end and he can only preach to the landside. For behind him there is nothing (it is the end of the world). So he preaches to the whole living things of the earth.
He preaches to the universe and also to the whole creation.
He stands on the water in a boat. He is the master of the water as God the creator was at the time of creation. And the miracle that takes place behind him in the sea is really a miracle. But it is also a parable for the viewers. Peter, the fisherman, who was a failure in catching fish that day, finds himself catching loads of them at the command of Jesus, son of a carpenter. But Jesus is in command.
And again this is a parable, because the kingdom of God will be like this. Human hands will catch nothing for the kingdom but it is the work of Jesus that will bring in loads of people into the kingdom that even boats (churches) will not be able to hold.
So Jesus preaches the kingdom to the universe, to the elements, to the earth – from the ends of the earth, and to the people. And the kingdom will have followers in great numbers as to sink the boats.