Monte Argentario, Giglio and Giannutri form a compact but unusually varied Mediterranean circuit. Base in Porto Santo Stefano for the broadest choice of local day boats, or sleep on Giglio for island evenings and quick access to its granite coast. Argentario contributes coves, pinnacles, caves and sheltered alternatives. Giglio adds steep granite walls, Posidonia meadows and classic offshore shoals. Giannutri is the protected, limestone counterpoint, with clear water, coralligenous walls and serious wreck options.
The destination is best treated as a local-operator trip rather than a liveaboard. May to October gives the easiest combined schedule, with June and September balancing warmth, boat frequency and crowd levels. Giannutri demands the most rule awareness: Zone 1 is closed to diving, while a February 2026 park decision temporarily permits scuba only in Zone 2 and confirms that no authorized buoy field is operating. Non-divers still get medieval Giglio Castello, Roman Villa Domizia, coastal forts, beaches and spring walking.