Yes, the sea can be considered a character, even a living character, in the novel "The Old Man and the Sea". Because, Hemingway personifies the sea, giving it human-like qualities, such as "the sea was very dark and the light made prisms" or "the sea was cruel".
The sea is depited as an active force, influencing the events of the story and shaping the old man's journey. It's not just a passive backdrop. While the sea is portrayed as having its own personality, with moods and temperaments, like a living being. It's described as "cruel", "beautiful", and "majestic".
The sea interacts with the old man, challenging him, testing him, and ultimately, redeeming him. Their relationship is central to the story and the sea represented the vast, unknowable, and powerful forces of nature, which the old man must confront and respect.
The sea is a constant presence, shaping the narrative and influencing the characters' actions. Its presence is felt throughout the story. and considering the sea as a character, even a living one, adds depth and complexity to the novel. It highlights the old man's struggles and triumphs, and underscores the themes of humanity's relationship with nature and the power of the natural world.