Besides walking away have you tried Fractual or fractional ownership?
Maybe advertise on the message boards asking for say 2 other investors at E80,000 each which would give you E160,000 to pay off the mortgage.
You would still have a holiday home and be rid of the mortgage problem'
Marinador is unfortunately not going to fall into the category of property for investment purposes in the near future.
nb I would estimate a forced sale value to be in the region of 150,000Euros