There's little to Cala Carbó, a pretty niche in Ibiza's southwest coast (9km southwest of Sant Josep), its shoreline a mix of sand and pebbles. You'll find good snorkelling offshore and a couple of popular seafood restaurants here, and it's a good, sheltered spot for families.
'Carbó' means 'coal' in Catalan: this bay was once used as a port for importing coal from the mainland.