Are you also afraid when you're in a boat in the storm?
The end has come, the boat is about to sink
Jesus sent His disciples out into the water ahead. He would come later. Jesus' disciples were quite scared on the boat. The waves were strong, because they were against the wind and the boat was in danger of sinking. They were on the boat and thought they were going to die. It's over, we're drowning, we're not going to make it to the other side. We're never going to see our friends and family again.
They thought they had it all, a ghost also walked across the water. The panic couldn't be bigger. Grown men who are afraid of a ghost, yes. It is possible. These guys proved it. They cried out in fear. They weren't as cool as they might have seemed in other situations.

The ghost is getting closer and closer