Greek Orthodox Hydra is said to have over 300 churches and chapels. The vast majority are family owned chapels or former parish churches that have fallen into disuse. These are typically opened once per year for the celebration of the name day of the saint to which they are dedicated. While not open to the public, they form picturesque points of interest in Hydra's landscape.
Hydra is also home to a number of monasteries and convents, some still inhabited by a few monks or nuns. Most are closed to the public, though it is possible to visit some, either by visiting during opening hours or by scheduling an appointment (generally before lunch in both cases). The institutions have long and storied histories, some even playing a unique role in the Greek War of Independence.