What is the director's intent behind the film's ambiguous beach ending?

[Steven_R]

I just finished watching that new psychological thriller everyone's talking about, and I have to admit the ambiguous ending has me completely puzzled. I think I understand the core twist regarding the protagonist's identity, but the final scene on the beach with the recurring symbol felt intentionally open-ended. For others who have seen it, what's your interpretation of the director's intent with that closing imagery, and do you think it suggests a cyclical nature to the events or a more literal, supernatural explanation that I might have missed?