On the 'learntarot' site she described it nicely--it's 'the blues', depression, moving into the land of the blues. I also look at it as misty shorelines, as the central figures & the boat mean more than the actual direction or goal being worked towards. It's a process of the journey, not the final destination. So by focusing on the people in the boat, there lies the main meaning of the card.
Abraham Lincoln was deeply mystical, and he sometimes told
of a recurring dream of his where he seemed to be on a river,
as he said, "in a singular and indescribable vessel,
but always the same~ moving with great rapidity
toward a dark and indefinite shore."
He believed it was a good omen.
Mary Todd Lincoln's interest in psychics would surely have
brought Tarot cards into their lives. They were very close.