Since July is high season, I would get in contact with a company a few days in advance asking for the details. We joined a boat tour with this company located in Cala Gonone : www.primasardegna.com/travel/minicrociera/ There were many boats visiting the coastline even at mid September, so the area can be pretty crowded, especially Cala Luna. I recommand joining a trip with a Zodiac, avoid larger boats that are cheaper but too much crowded.

The driver was paid. We joined a boat tour with this company www.primasardegna.com/ located in Cala Gonone. Many companies in the area offer a variety of boat tours to visit the coastline; some of the companies also offer the possibility of renting the boat alone, but usually they offer guided tours including the driver.