DAY TRIPS FROM AMSTERDAM
Since the Netherlands is quite small you can easily and quickly visit a nearby city all you need to do is purchase the Amsterdam & Region Travel Ticket in addition to your I amsterdam City Card.
Voldenam & Marken are where you need to be. While they are two different cities you can visit both in one day and the ferry from one to the other is included in your I amsterdam City Card.
Voldendam & Marken