Info about the waters surrounding the Old Town
The 4 islands of the Old Town is situated between the Baltic Sea and the large lake Mälaren, this is one of the main reasons that the city was founded here in the first place at the years after 1 000 A.D. This also means that today a lock is needed for ships travelling from the Baltic Sea to the lake Mälaren. The first lock was built in the mid-17:th century and before that during a couple of hundred years the ships were drawn by hand into the lake. However, before 1200 A.D, the lake didn't exist, it was just a bay of the Baltic Sea.