Connect with your spiritual side and offer up your own prayer at Church of Saint Nicholas. Quietly reflect outside for a while or ask if you're allowed to join the next service.
You'll have no end of sightseeing choices when in Karystos. Church of Saint Nicholas is a good place to start here, but there are many other worthy attractions to enjoy. Bourtzi Castle, Marmari Harbor, and Agia Paraskevi Beach are near the house of prayer and will round out your day nicely.