They might look like identical carbon copies on a brochure, but P&O’s flagship sister ships have completely different personalities, dining setups, and holiday destinations.

When you are looking at the two largest vessels in the British cruise fleet, a direct comparison of P&O Iona vs Arvia can make them seem entirely identical on paper. Both are massive, liquefied natural gas (LNG) powered Excel-class ships. Both weigh in at over 184,000 tonnes, span 19 decks, and carry over 5,200 passengers at full capacity.

However, any seasoned cruiser who has stepped aboard both will tell you that the onboard experience is vastly different. P&O Cruises deliberately altered the structural layout, the restaurant configurations, and the entertainment decks when building Arvia a year after Iona.

If you are trying to decide which mega-ship fits your family’s holiday style, you need to look past the shared blueprints. In this structural guide, we break down the hidden design tweaks, the major dining room shifts, and the itinerary profiles that set these two maritime sisters apart.

Shared Specs vs. Unique Identities

While they share the same hull design and basic structural bones, their outdoor features and operational focuses are tailored to completely different climates.

Feature	P&O Iona	P&O Arvia
Launch Year	2021	2022
SkyDome Roof	Fixed glass dome	Retractable sliding glass roof
Main Dining Rooms	4 (Pearl, Opal, Aqua, Coral)	2 (Zenith, Meridian)
Unique Free Dining	Traditional Main Dining Rooms	6th Street Diner / The Olive Grove
Unique Paid Dining	The Keel & Cow (Gastropub)	Green & Co feat. Mizuhana (Sushi & Plant-Based)
Outdoor Activities	Traditional open decks, infinity pools	Altitude Skywalk (Ropes), Minigolf, Splash Valley
Primary Destinations	Norwegian Fjords & Northern Europe	Mediterranean (Summer) & Caribbean (Winter)

Layout & Space Changes: SkyDomes and Sports Decks

The most significant physical divergence between the two ships sits right at the top deck under the massive glass SkyDome.

The SkyDome Showdown

On Iona, the SkyDome features a completely fixed glass roof. This is ideal for her primary routing through the stunning, cool climates of the Norwegian Fjords. It acts as a massive, warm conservatory where passengers can view the mountains and waterfalls without freezing on deck.

On Arvia, the SkyDome was upgraded to feature a fully retractable sliding glass roof. Because Arvia spends her seasons chasing the hot sun of the Mediterranean and the Caribbean, this roof slides wide open on sea days, turning the indoor pool area into a traditional, open-air sun deck. However, note that the internal staircases on Arvia’s SkyDome were shifted inboard, which can make the pool deck area feel slightly more congested on busy days compared to Iona’s layout.

Deck 19: Traditional vs. High-Octane Action

Move to the top sports decks, and the structural differences become even more obvious:

• Iona’s Deck 19 focuses heavily on peaceful relaxation, offering traditional open deck space, clean sightlines, and beautiful infinity pools looking out over the ship’s wake.
• Arvia’s Deck 19 was completely transformed into the Altitude activity zone. It features a full-scale 9-hole minigolf course, a high-ropes adventure course called the Altitude Skywalk hanging 54 metres above the ocean, and the Splash Valley aqua zone for kids.

Dining & Entertainment Divergence: The Main Dining Room Shift

The most critical operational difference you will encounter on board involves your evening meals. P&O fundamentally redesigned how traffic flows through the restaurants on Arvia, and it directly impacts virtual queuing times.

Iona: The Traditionalist’s Haven

Iona operates with four standard Main Dining Rooms (MDRs): the large Pearl and Meridian restaurants, and two smaller, intimate venues called Aqua and Coral. Because there are four distinct dining rooms included in your base cruise fare, the capacity for traditional sit-down table service is massive, keeping virtual queues on the My Holiday app running smoothly.

Arvia: The Alternative Eatery Experiment

On Arvia, P&O eliminated the two smaller main dining rooms completely. Instead, they operate only two Main Dining Rooms (Zenith and Meridian). The physical spaces occupied by the smaller dining rooms on Iona were converted into alternative dining spaces:

• 6th Street Diner (Included/Free): A highly popular, retro American-style diner complete with jukeboxes, booths, and comfort food classics like fried chicken and waffles.
• Green & Co feat. Mizuhana (Paid): A premium, incredibly fresh plant-based and sushi speciality restaurant where you pay per item or a fixed cover fee.

Furthermore, The Olive Grove (the Mediterranean venue) is a fully included, free alternative restaurant on Arvia, whereas on Iona it operates on a hybrid menu where several items carry an additional upcharge.

The Result: Because Arvia has fewer standard dining room seats, the virtual queues for the main formal restaurants can back up significantly during peak dining hours. However, she offers a much wider, more eclectic variety of casual and street-food style choices across the ship.

Choose Your Sister Guide

Ultimately, choosing between these two Excel-class powerhouses comes down to matching the ship’s hardware to your destination preferences and family dynamic.

Book P&O Iona if:

• You are heading to Norway: Her fixed glass dome and spacious indoor viewing lounges are tailor-made for cruising through cool Fjord valleys.
• You prefer traditional dining: The 4-MDR configuration means getting a standard table for a multi-course dinner is faster and simpler.
• You want a calmer vibe: Without the ropes courses, minigolf lanes, and diners, Iona naturally attracts a slightly more traditional, relaxed demographic of cruisers.

Book P&O Arvia if:

• You are chasing hot summer sun: The retractable sliding roof over the SkyDome creates an incredible tropical resort atmosphere when sailing the Med or the Caribbean.
• You have active kids or teenagers: The high-ropes course, minigolf setup, and Splash Valley keep energetic family members occupied for hours on sea days.
• You love diverse casual food: If you get bored eating in the same main dining room every evening, Arvia’s inclusion of the 6th Street Diner and the fully free Olive Grove offers superior culinary variety.