The meaning of that Jordan's near-death experience is tied in with what happened in Chapter Three of the Book of Joshua. There, the people’s passage into the Promised Land was blocked by the Jordan’s being in a wide and deep flood.
Joshua ordered the priests carrying the Ark of the Covenant to step boldly into the flood, as well, he ordered the people to bravely follow the Ark. The waters backed up, and the Ark took up its position at the bottom of the riverbed, allowing all the people to pass by into the Promised Land.
The tie-in to today’s Gospel rests in our realization that the Sea of Galilee where they experienced that storm was actually just a wide stretch of the Jordan River. As such, it too became a symbol for death blocking the way to the Promised Land.
Mark let us see that the stormy lake stood for the regions of death by having the disciples identify Jesus as a ghost.
The Gospels never tell us stories for the sake of telling good stories. Each story is principally a lesson. The lesson here is that just as the Ark made way for the Israelites to pass into the Promised Land, so Jesus will be there in the regions of death, making a way for you to pass into heaven.