The Skiathos open air cinema is located in Skiathos Town on Papadiamantis Street. It opens during tourist season and offers a few different films, but by far and away the most popular is Mamma Mia!. As you likely know, as it is hard to escape the fact, the blockbuster musical based on the music of ABBA was partially filmed in Skiathos, with the rest being filmed in Skopelos, the island neighbouring Skiathos, and in Pinewood Studio in the UK.
The cinema its self can hold around 200 people comfortably and is open topped so you can enjoy the film under the stars and night starts to draw in. It has a snack bar that serves you soft drinks, wine, beer and your obligatory popcorn. This is open for the duration of the film and before it starts. Toilets are easily accessible.
Whilst it is common for people to sign along and even get up for a dance, you will not be forced to and it will not affect your viewing pleasure. The sound is loud enough to mask the enthusiastic signing and the screen big enough. There are a few surprises during the showing but I will not spoil them.