The Province of Caltanissetta is in the southern part of Sicily, Italy. It contains 22 comuni, which are listed at Comuni of the Province of Caltanissetta. The River Salso is the main river of the province; it is 122 kilometres long and originates in the province of Palermo, and it flows into the Mediterranean in this province at the end of the Gulf of Gela.
The province extends to the central part of Sicily in the northwestern direction where the capital is located. The commune of Resuttano is found in an enclave of the province of Palermo near Caltanissetta between Monte Stretto and Portella del Vento. The land extends to the Gela Plain and into the Gulf of Gela, where the main river of the province, the Salso, meets the Mediterranean.