What are the options for tansferring from Monastir airport to Mahdia?

Only just noticed this, so sorry for the late reply.

It depends what time you arrive...there is the "Sahel Metro" which runs from Sousse through Monastir and the airport down to Mahdia, although this doesn't run late at night. If you arrive on a charter flight (or at the same time as one), there may be coaches laid on for tourists heading down to the hotels in Mahdia, and you might be able to talk your way on board. otherwise, you'll have to negotiate a fare with a taxi driver...it's not that cheap!

Thank you for your answer. We have actually arranged for a taxi pickup through the people with whom we are staying. The cost is dinars 20 which I don't think is too bad, seeing that I saw a one way fare for a shuttle service was £26. Unfortunately we couldn't use the metro as we are arriving quite late.

Just a question on the off-chance - have you used the dive school in Mahdia? If so, what's your opinion?