Ischia has 21 km of coastline and beaches that range from sandy family stretches to volcanic-black coves. Most of the best ones have lidos (beach clubs) that charge an entry fee including sun lounger and umbrella; free public sections usually exist at the edges.
Maronti (near Barano) is the longest beach on the island — 3 km of sand with thermal springs emerging from the shore. Water taxis run there from Sant'Angelo; there's also a road from Barano. Less crowded than most.
Citara (Forio) is popular and accessible, with the Poseidon Thermal Gardens adjacent. Most of the beach is privately managed but free sections exist.
Spiaggia degli Inglesi (English Beach, near Ischia Porto) is small and rarely crowded. Calm water.
Fumarole (near Sant'Angelo) is where geothermal steam rises through the black sand. The volcanic origin gives the water a slight warm tint. BBQ facilities on the beach.