You don't need to be of strong faith to enjoy the serene atmosphere of Hydra Cathedral. Look up when the next mass is scheduled or when it's open for general viewing.
This principal church is often on the itineraries of visitors to Hydra Town. But Hydra Cathedral isn't the only drawcard here. Hydra Town Harbour, Mandraki Beach, and Hydra Merchant Marine Academy are some other worthwhile attractions close by.