As we mentioned previously all Finale (6.16/6.17/6.18) spoilers will be behind Are You Sure buttons and cannot be discussed outside of the post itself.
Jack, Kate, Desmond, Hurley, Sawyer, Faraday, and Minkowski . All I know about this is they will be working in water, fully submerged. Sorry not sure if this is Alt or on Island. I believe this is the 1st epi of the 3 part final.
They are still finishing up filming on the Jacob/MIB epi today on a separate unit. I think that episode is solid flashback of Jacob/MIB, with very little or no current Island action.