"When He had finished speaking, He said to Simon, 'Put out into deep water, and let down the nets for a catch'" (Luke 5:4).
Jesus had been sitting in the boat with Simon in shallow waters. Even there, Simon saw Jesus do amazing things, speaking to such a large and spontaneous crowd. And then He challenged Simon to go out into the deep for a catch. He called Him out into the "mystery" of the unknown, a place that seemed so vast where uncertainty was the only thing that was certain.
It's not so hard to hold back and tread water where you know you can closely touch, but God called you to put out into the deep, to trust Him in the mystery of the unknown. When He calls, your uncertainty is irrelevant because you can be certain that He is faithful and you can trust Him. Therefore, you cannot allow fear and intimidation of deep places to keep you trapped in shallow water!