Aegina is not a white-sand island — most of its beaches are made of dark pebbles or coarse sand — but the water is clear, the crowds are manageable compared to the Cyclades, and the variety is surprisingly good for an island you can cross in under an hour.
The town beach just north of the port is convenient but nothing special. It is fine for a quick dip after the ferry, but most visitors push on. Agia Marina on the east coast is the island's main resort beach: a long sandy arc with sun beds, tavernas, and calm, shallow water that makes it ideal for families with small children. Buses run there from the port several times a day.
For something quieter, head south. The beach at Perdika is a narrow strip of pebbles with exceptional water clarity and a handful of fish tavernas right at the edge. From Perdika you can also catch a short boat to the small islet of Moni, which has no facilities but beautiful snorkelling and a population of deer and peacocks that have made the island their own.
Marathonas, just a few kilometres south of town, is a good middle ground — some sand, some pebbles, not too busy, and easy to reach by bicycle or scooter. If you rent a vehicle, the road along the west coast passes several unmarked spots where a path down to the water rewards anyone willing to scramble.
Photo: C messier / Wikimedia Commons (CC BY-SA 4.0)