In her final monologue, Blanche imagines herself dying at sea after eating an unwashed grape. The situation seems to be one of relative opulence, on a yacht or a luxurious ocean liner, where the ship's doctor is young and handsome and has a big silver watch. Blanche's life has followed a downward spiral, from the grandeur of Belle Reve to the squalor of seedy hotels in Laurel to her sister's cramped apartment in New Orleans. Her end, she fears, may be even more squalid than anything she has seen so far. This is why she imagines a clean death for herself, on a ship in the midst of a clear blue sea.
In her own mind, Blanche is a pure woman. Her transgressions have been a way of coping with a life which has not lived up to her dreams. She likes to think of herself as so pure and refined that the slightest hint of dirt, even so much as might cling to the skin of an unwashed grape, would be enough to send her straight to heaven. She has an affinity for white (indeed, it is the meaning of her name, as she tells Mitch), and it is only fitting that she should be sewn up in a pure white sack to be consigned to the depths of a pure blue sea. This is a pauper's burial, and one that leaves no trace, but the vivid color and romantic details confer upon Blanche's death a peace and dignity denied to her tumultuous life. By embroidering this tale out loud, Blanche follows a strategy she employs often in the play, of using her eloquence to impose fantasy on reality.