It tells the story of a heroic effort to salvage a sunken ship, the eponymous Mary Ellen Carter, by members of her crew.
The song chronicles the efforts to salvage the ship, implying that it will be raised on the following day: We've patched her rents, stopped her vents, Dogged hatch and porthole down, Put cables to her fore and aft And girded her around.
The song ends with an inspirational message to people "to whom adversity has dealt the final blow": Never give up, and, "like the Mary Ellen Carter, rise again!"
His snorkeling experience helped him avoid panic and swim to the surface, but he was left to spend the night alone on a partially deflated lifeboat he eventually reached, in water barely above freezing and air much colder.
[9] And you, to whom adversity has dealt the final blow With smiling bastards lying to you everywhere you go Turn to, and put out all your strength of arm and heart and brain And like the Mary Ellen Carter, rise again.