There are 65 beaches on Skíathos...

I'm not a beach person, probably because I was always the most likely to have sand kicked in my face by the guys who had bought the Charles Atlas system. 

I've visited seven on Skiathos - Troulos where we swim every morning very early then leave before the tourists pile out, Koukounaries where we turned round and pretty much ran away from the crowds, one just up the northerly track from there (dunno the name, just a quick glance at the devastation caused by a storm), Asselinos for a friendly drink stop, Ligharies for a great Greek salad, Kechria for the steps of doom and Greek salad, Xanemos which always strikes me as dusty, windy and/or dirty (but it's lots of people's favourite). 

We have never hired sun beds and umbrellas and never will. The idea of spending the day with those things fills me with horror. 

But I would happily seek out every one of the Skiathos ones for the joy of traveling through the lovely countryside. 

Have a a look at Woody's map. I don't expect he's got them all marked, but there are a good number. 

EDIT - Sorry, eight beaches - Kanapitsa - it's like how you describe Maratha, very narrow. Maybe nine if Sklithri counts too, beach narrow enough to qualify for your award system. 

My avatar is a picture of my favourite beach.  No sunbeds, no name (at least none that I am aware of) and usually, nobody else there! Heaven!
Bob

Yes Kate, but if you've signed the Official Secrets Act I could let you know.

oK, Kate,  but don't tell anyone else. Get off the bus at BS 21 and walk in the direction of Koukounaries. Keep your eyes peeled and you will spot a path going down on the left. Take care as it is a bit steep in parts, but definitely worth it when you reach the beach, particularly if there is no one else there. Remember now, don't tell anyone else!
Bob