Why did John record the story of Jesus' third appearance to the disciples at the Sea of Galilee? None of the other Gospels mention this story.
It seems the apostles had gone back to their normal, every-day work. They were fishing in the Sea of Galilee. When Jesus first called these men it was at the Sea of Galilee. Luke 5 tells the story of how Jesus commanded Peter to let down his nets for a catch after Peter had been fishing all night and caught nothing. Peter obeyed and caught a tremendous quantity of fish. The clear teaching was Jesus can provide the catch - Peter just needed to obey Him. Jesus said to him at that time, "Do not fear, from now on you will be catching men."
In John 21 we read a similar story. At first, the disciples didn't know it was Jesus on the seashore calling them to cast their nets on the right-hand side of the boat. They obeyed and again were not able to pull the nets in because of the great number of fish. The "disciple whom Jesus loved" (John) quickly realized this was the Lord and told Peter, who jumped overboard to swim to the shore.
Why did Jesus do this? Perhaps He wanted to REMIND the disciples they had work to do. He wanted to REMIND them He still could provide for them, just as He had in the past. He wanted to REMIND them they had a special divine charge to preach the kingdom to mankind.
We need this kind of reminder. It's so easy to get caught up in the daily grind at work and forget our REAL marching orders come from Jesus Christ. Not that we shouldn't be working to support our families and so that we'll have something to give to the poor, but even in our work we realize our first directive is to uphold the kingdom of Christ. I don't believe Jesus is going to appear to me to give me this reminder. But He has given me His word that I can use as a reminder every day. If we don't continue reminding ourselves of our direction and purpose, we will wander off course. We will find ourselves working for all kinds of purposes under the sun, but we will leave out the kingdom.
"But seek first His kingdom and His righteousness, and all these things will be added to you" (Matt. 6:33).
Nathan