Tsougria beach is not part of the Skiathos
mainland, it’s actually an islet across from the port of Skiathos town
There’s a regular boat service from the harbour which costs about 10 Euros for an open ended return trip and there tends to be 2 or 3 trips out in the morning and the same coming back in the evening so you can get whichever one suits you best. Alternatively you can get one of the boat trips that travels around the island as some of them stop off at Tsougria beach.
Once on Tsougria there is a lovely sandy beach with colourful shallow waters that are great for kids. There’s a taverna selling delicious food and drinks, there are sun loungers with umbrellas to hire but no water sports. There’s loads of space away from the loungers to stake out a bit of space to yourself.
Generally speaking the beach is fairly quiet, you may even find you’re sharing the beach with just a handful of other people at some points in the day. The only caveat to that is that when a boat trip or 2 arrives the atmosphere changes completely and it then starts to feel a bit busy.
There are other beaches on Tsougria island but they tend to have stones around the waters edge and there’s no facilities on those beaches either. There’s a charming little church on the hillside just south of the main beach which is a nice place for a wander or to get some photos of the island.