Walk off the ship to Quai des Belges and board a National-Park-authorized boat that threads the 12-mile wall of blinding-white limestone cliffs plunging into fjord-like turquoise inlets: Sormiou, Morgiou, Sugiton, En-Vau, Port-Pin and Port-Miou. This is the one signature landscape Marseille is built around, and the boat departs the Vieux-Port itself, so there is no need to bus over to Cassis first. On a warm port day, pick the version with a swim stop and float in a cove no road reaches.
What to expect
You walk straight off the ship to Quai des Belges and board a National-Park-authorized boat that launches directly from the Vieux-Port into one of Europe's most stunning seascapes. For the next three to three-and-a-half hours, you glide beneath a 12-mile chain of blinding-white limestone cliffs plunging into fjord-like turquoise inlets—Sormiou, Morgiou, Sugiton, En-Vau, Port-Pin, and Port-Miou—with panoramic deck commentary unfolding the geology and history. On warm days, the summer "Calanques & Baignade" version anchors in a pristine cove reachable only by water, where you float in crystalline turquoise that no road can touch.
Biggest markup of the day, direct wins decisively. The cruise line's Cassis/Calanques boat excursion runs $130-170 pp (RCI's was reported at $133) for essentially this same boat ride after a coach transfer to Cassis. Booking Icard direct from the Old Port is ~$36-44 pp: you save roughly $90-130 per person AND skip the Cassis bus. Just confirm the last return slot leaves you 90+ min of margin before all-aboard.
Good to know
Book Icard Maritime directly at the pier rather than through the cruise line—you'll pay €33–40 ($36–44) instead of $130–170, saving $90+ per person while skipping a Cassis coach transfer. The 3h15 and 3h30 cruises depart Quai des Belges (a five-minute walk from most ships) multiple times daily; confirm the final return slot leaves at least 90 minutes before your ship's all-aboard time. Bring sunscreen, a hat, and a swimsuit if opting for the baignade version; no need to book ahead—just show up at the departure quay and purchase tickets on-site.