Unknown Octopus

I found this while diving in Thailand (Andaman Sea), have not been able to identify it.

Any Suggestions? (Yes there is an Octopus in this picture).

Difficult as they can all change colour and skin patterns. It seems to have an eye spot on the mantle below the eye, but the spot does seem to have a line through. The eye spot would indicate a day octopus. Could also be a mosaic octopus which is reported to have a series of white dots on its upper arms.