5 Best Sights in The Saronic Gulf Islands, Greece

Internationally renowned modern art collector Dakis Joannou acquired this former Hydra slaughterhouse, a leisurely 10-minute walk from the town (toward Mandraki), in 2009 to host artistic events and projects organized by his budding DESTE Foundation. Surprisingly, this is not what you might expect a chic and modern art gallery to look like: housed in an unassuming small building on a cliff by the sea, it can be missed if you don't actively look for it. But perhaps that is exactly the point that Joannou wanted to make with the Slaughterhouse, which has already acquired a leading role in Hydra's cultural life. Starting with the 2009 multimedia project "Blood of Two" by Matthew Barney and Elizabeth Peyton (which paid homage to the space's morbid past), every summer the space is now assigned to a different artist who is invited to stage a site-specific exhibition. Since then Doug Aitken, Urs Fischer, Paul Chan, Pawel Althamer, Jeff Koons, and Kara Walker, among others, have had works and installations exhibited there.

Just beyond Marathonas, this mostly sandy bay with crystalline green water is fringed by eucalyptus and pine trees. Shallow depths suit young swimmers; the beach bar rents loungers, runs a volleyball court and hosts low-key DJ sets on summer weekends. KTEL buses to Perdika stop about 200 meters (656 feet) above the beach. Amenities: food and drink; parking (no fee); showers; water sports. Best for: sunset; swimming.

The best sandy beach on the island, Agia Marina is popular with the parenting set, as the shallow water is ideal for playing children. A rockier stretch just north of the pier offers good diving and snorkeling. Tavernas and cafés line the bay, and the Apollo Resort Hotel is a short walk away. Amenities: food and drink; lifeguards; parking (no fee); toilets; water sports. Best for: snorkeling; swimming; walking.

The town's stone promontory is the site of the little 19th-century church, Agios Mamas—take your photos from a distance as the church is privately owned and often locked. Bring a swimsuit, as the beach here is great for a dip.

Sandy Marathonas A beach offers excellent swimming on the island's west side. Beyond the village, Marathonas B provides another beautiful stretch. Both beaches feature rental sun beds and umbrellas but get crowded in summer—arrive early for prime spots. The western location delivers spectacular sunset views, making staying till evening particularly magical. Amenities: food and drink; lifeguards; parking (no fee). Best for: sunset; swimming.