There are 6 monasteries and 300 churches on Hydra, a relatively large number considering the size of the island.
It is really worth visiting the twin monasteries of Agia Evpraxia and Prophitis Ilias where Kolokotronis and other fighters were imprisoned for a time in 1825. Also of great interest are the monasteries of Agia Triada, Agia Matrona, Agios Nikolaos, Theotokos of Zourva, Kimisis tis Theotokou (17th century), the Ecclesiastic and Byzazntine Museum as well as the churches of Candlemas and Agios Ioannis the Faster with its rare and beautiful 18th century frescoes.
The nearest church to the center of the port is the Hydra Cathedral. Panagia Faneromeni -another church worth visiting- stands out for its tall bell tower and big clock. There are other churches with beautiful domes supported by marble arches, like those of Agios Ioannis and Candlemas. The newest church on the island is dedicated to Agios Konstantinos of Hydra.