Getting off the bus at stop 24, the end of the line, you can walk over the hill to the 2 Banana Beaches on the west side of Skiathos.
Big Banana, the main beach, is a beautiful beach and very popular, especially with younger tourists. It used to be the naturist beach but most people who like to bathe & sunbathe naked, now go to small Banana Beach which is also known as Spartacus Beach. This is a short walk around the rocks to the right of Big Banana. This also the beach where a fair amount of gay people go but is also frequented by singles and families. Greece being a fairly democratic place, everyone usually co-exists quite happily.
Big Banana has a water sports school and is the best place for windsurfing as there is a good cross shore breeze and good waves out in the channel between Skiathos and Pelion. Unfortunately, it is difficult to get your gear down to the beach as the road is closed and there is no up to date stuff to be rented. In the evening, as the sun goes down, both these beaches are wonderful for sunsets.