Diamante's main beach runs the full length of the town, three kilometres of mixed sand and pebbles backed by the lungomare. The water is unusually clear for a beach right next to a town, thanks to the steep drop-off just offshore and the absence of any major river. Pieces of the bottom are stony, so water shoes are useful.
The central stretch is busy with paid stabilimenti — sun-loungers, umbrellas, beach bars, ten or fifteen euros for a basic setup. The free public beach at either end is wide enough that you can always find space outside the August peak. Look for the small black-sand patches near the southern end, a reminder that this whole coast is volcanic in origin.