If I were to be stranded in a desert island for a year, there are three books which I would choose to take with me.
The first would be a wilderness survival guide, because it
would help me survive in the island. I do not have much knowledge in surviving in wilderness, and it will be hard especially without any surviving gears and technology. Although literature and mental health is also important to overcome loneliness and fearful environment, I believe survival and establishing the shelter for protection and relaxation is also critical to mental wellness.
The second book I would take would be physics textbook. I think that would be a great recreational activity, and help keep thinking abut something and keep myself focused on something.
The third would be a book about thinking positively, because it will be important to have positive mind and be optimistic than pessimistic in order to keep myself away from mental illness.