If you in for a small adventure Avgo monastery offers a very peaceful environment with great views. It is about 35 minutes drive from Ermioni with a rough road for the last 10-15 minutes. Then you can explore the Avgo Monastery of the Holy Great Demetrius. It seems that the monastery operated in the middle ages, perhaps the 2nd half of the 15th century or the 1st half of the 16th, while sources of 1700 state that it had 16 monks and an equal number of servants.
Please ask us for instructions before you go, unless you have really done your research well!