The Historical Archives Museum occupies a handsome 19th-century stone mansion on the east side of the harbour and houses Hydra's collection of maritime documents, ship models, paintings, weapons, and the personal effects of the island's revolutionary leaders. The collection is far more substantial than the modest building suggests — Hydra played an outsize role in the 1821 War of Independence, and the museum's archive of ships' logs, letters, and Ottoman-era trade documents is a serious historical resource.
For the casual visitor, the highlights are the model ships, the embalmed heart of admiral Andreas Miaoulis (a Hydriot icon), and the upstairs gallery of 19th-century maritime paintings. Allow forty-five minutes. Entry is cheap and the museum is air-conditioned — a worthwhile half-hour escape from the midday glare on the quay.