Dont miss this beach when your wisiting Norrtälje. Nice clean beach, warm water, shallow water great for kids, free parking 50 meters from the beach. There is also a cafeteria that serves sandwiches, coffey and soft dinks.
Dont miss this, the place is called KÄRLEKSUDDEN. Go out on the webb and klick on Kärleksudden.
The scenic "summer cottage islands" outside Furusund are nice. Yxlan is known for good swimming from its cliffs and not for a lot of sights itself. It is however the island you get to first by road ferry from Furusund on your way to Blidö and as scenic as many others, so you might as well have a look at it. Blidö, reached by yet another road ferry, has an archipelago inn (www.blidowardshus.se/ ) and a 19th century church as well as a nature reserve with island meadows. You can also rent canoes here for exploring the archipelago further and now you're not far from the real outer archipelago with its rocky skerries: http://www.blidokajak.se/