Sun Princess: Sphere Class Ship Guide

What makes Sun Princess feel so different from the Princess ships that came before her? She is the first of the new Sphere class, a clean-sheet design that throws out the old Princess playbook and starts over with light, glass and the sea as the organizing idea. At roughly 177,000 gross tons, 21 decks and about 4,300 guests, she is the largest ship Princess has ever built and the line’s first dual-fuel LNG vessel. This guide walks you through the spaces that define her, from the geodesic Dome at the top of the ship to the reimagined three-deck Piazza and its outward-facing suspended Sphere, and shows you where to sit, where to watch shows, and where to escape when you want quiet.

If you are still deciding whether Sun Princess is the right ship for you, start with our broader Sun Princess cruise guide. This article is the architecture-and-spaces deep dive: what Sphere class actually changes, and how to use the ship once you are aboard.

What Sphere class actually means

Older Princess ships share a family resemblance: a central Piazza atrium ringed by shops and cafes, a promenade of dining rooms, a pool deck up top, and a theater forward. Sphere class keeps the DNA but rebuilds the skeleton. Because she was designed from scratch around a new hull and a dual-fuel LNG propulsion system rather than stretched from an existing platform, the naval architects had room to do things that retrofits never allow: taller interior volumes, more glass on the outer walls, and public rooms that push toward the sides of the ship instead of hiding in the middle.

The practical result is a ship that feels lighter and more connected to the water than her predecessors. Where older Princess vessels wrapped their busiest spaces in interior walls, Sun Princess turns them outward. You notice it first in the atrium, which now climbs three decks and reaches toward the hull with a glass-walled Sphere that hangs out over the ocean. You notice it again at the top of the ship, where The Dome replaces the usual enclosed lounge with a geodesic glass structure that opens the sky. The whole design language is about sightlines: from most of the major public rooms, you can see the sea.

LNG matters here too, and not only for emissions. A dual-fuel ship is quieter and smoother in many of the spaces guests actually use, and the newness means the technology running underneath the experience, including the MedallionClass system, is the most current in the fleet. If you have sailed Princess before and loved it but found the ships starting to feel dated, Sphere class is the answer to that specific complaint.

The Dome: the space everyone talks about

The Dome sits at the very top of the ship, a geodesic glass enclosure inspired by the terraces of Santorini. It is the single most distinctive room on Sun Princess, and it does two completely different jobs depending on the time of day. By day it is an indoor-outdoor pool retreat, flooded with light, with the glass shell keeping it comfortable whether the Mediterranean sun is blazing or a breeze has picked up at sea. By night the pool area transforms into a theater staging Cirque Éloize acrobatic shows, with the glass dome as a dramatic backdrop.

Because it changes character, timing is everything. In the morning and early afternoon The Dome is one of the calmer sun spots on the ship, especially on port days when many guests are ashore. It is a genuinely lovely place to swim while the ship is sailing between Greek islands. In the evening it becomes a ticketed or reserved entertainment venue, so if you want to see the Cirque Éloize show, check show times in the Princess app and plan to arrive early for a good seat. The best views are from the tiers facing the performance floor; because the space is compact compared to a traditional theater, there is no truly bad seat, but the front rows fill first.

The Piazza and the Sphere: the new heart of the ship

The Piazza is the social center of every Princess ship, and on Sun Princess it has been rethought as a three-deck atrium hub. The headline feature is the Sphere: an outward, glass-walled structure suspended off the side of the ship, giving expansive ocean views from what used to be a purely interior space. Instead of looking inward at shop windows, guests in the Piazza now look out at the water. It is the clearest single example of the Sphere class philosophy.

The Piazza also carries a movable LED screen for live entertainment, so the space can host everything from daytime music to evening performances without the fixed staging of an older atrium. The three-deck height gives the room the acoustics and sightlines to work as a performance venue, and the balconies on the upper levels turn into informal viewing galleries when something is happening below.

Around the Piazza you will find the anchors of daily life aboard. The 24-hour International Café is here, the most useful single spot on the ship for a coffee, a pastry in the morning, or a light savory bite at odd hours. Alfredo’s and Gigi’s handle pizza, O’Malley’s is the Irish pub, and the whole zone is where you naturally end up between activities. If you want to understand the rhythm of the ship, spend your first evening people-watching from a Piazza balcony with a drink; you will quickly see how the space threads the entertainment, dining and social life together. For a fuller sense of the daily flow, our guide to what to expect on Sun Princess covers the routines beyond the architecture.

Where to sit in the Piazza

The lower level puts you closest to the action and the movable LED screen, best when there is a performance. The middle and upper decks are quieter and give you the long view down into the atrium and out through the Sphere. For a calm coffee, the upper balconies are the pick; for the energy of live music, take a low table near the screen and settle in.

The Sanctuary Collection: the adults-only retreat

The Sanctuary has long been Princess’s adults-only sun retreat, and on Sun Princess it has grown into the Sanctuary Collection, an expanded suite-and-retreat concept. It pairs an adults-only relaxation area with a private sun deck, a pool and exclusive dining, and it links to a tier of suites whose guests get retreat access as part of the room. If you value calm above all, this is the part of the ship built specifically for you.

There are two ways to experience it. If you book a Sanctuary Collection suite, the retreat, its private sun deck and pool, and the exclusive dining come with the stateroom; it is the top of the range for a reason, and on a warm, port-heavy Mediterranean itinerary the private deck is a genuine luxury on sea days. If you are in another cabin category, check whether day access or passes are available in the Princess app; availability varies, so confirm rather than assume. Either way, the Sanctuary is the reliable answer to the question every big-ship guest eventually asks: where do I go when 4,300 people feel like too many?

Pools and open decks

Sun Princess spreads her water and sun across several distinct areas rather than piling everyone into one main pool, which is one of the quiet advantages of a clean-sheet design. The Sea Breeze and Terrace pools handle the main daytime crowd, and there is a wake-view pool aft, which is the one to seek out if you want to sit with a drink and watch the ship’s wake stretch behind you toward the horizon. The Dome’s pool, covered above, is the light-filled retreat up top.

Movies Under the Stars, the giant poolside LED screen that is a Princess signature, plays over the main deck, so an evening film under a warm Mediterranean sky is one of the easy pleasures of the ship. The Lotus Spa handles wellness, with the usual thermal and treatment spaces. The trick to the open decks on any big ship is knowing where the crowd is not: on Sun Princess, the aft wake-view pool and the upper-deck edges away from the main pool tend to stay calmer, while the central Sea Breeze zone is the busiest by design.

Dining across the ship

Sun Princess carries a large and genuinely varied dining lineup, and the Sphere class layout gives many of the venues better views than they would have had on an older ship. The backbone is three main dining rooms, where you can keep traditional set dining or use flexible Dine My Way to reserve times through your Medallion, plus the Horizons buffet for casual meals.

The specialty and casual roster is where the ship shows off. Love by Britto is an artistic prix-fixe experience with wake views. The Butcher’s Block by Dario is a Tuscan butcher-style steakhouse, and the Crown Grill is the more classic steakhouse. Makoto Ocean handles Edomae sushi, Sabatini’s is the Italian trattoria, and The Catch by Rudi focuses on seafood. Add Alfredo’s and Gigi’s pizzerias, O’Malley’s Irish pub, and the 24-hour International Café by the Piazza, and you have enough range to eat somewhere different every night of a long Mediterranean voyage. OceanNow and room service deliver across the ship, so a light meal can also come to you at the pool or the cabin.

A practical tip: the most popular specialty restaurants book up, especially on sea days and on the first and last nights, so reserve your priority venues in the Princess app before you sail. If you are new to the reservation system, our MedallionClass first-timer guide walks through Dine My Way and OceanNow step by step.

How MedallionClass ties it all together

The reason a ship this large can feel manageable is MedallionClass. Every guest wears an Ocean Medallion, a quarter-sized wearable that unlocks your stateroom hands-free, speeds up boarding, lets you locate your travel companions, and handles touchless payments. On a ship where the person you are trying to meet could be anywhere across 21 decks, the locator feature alone earns its keep.

Through OceanNow you order food and drinks to wherever you are, whether that is a lounger at the wake-view pool or a seat in the Piazza. Dine My Way lets you reserve flexible dining times or keep a traditional set seating, and JourneyView helps you plan the day around shows, ports and meals. To get the full benefit from the first minute aboard, set it up before you sail: download the Princess app, complete the OceanReady check-in, add a payment method, and order your Medallion so it is waiting for you. Doing this in advance is the difference between walking straight onto the ship and standing in a line.

Sphere class versus older Princess ships

If you are choosing between Sun Princess and an older Princess ship, here is the honest comparison. Sphere class gives you more space, more glass, the newest technology, and signature rooms, the Dome and the outward Sphere, that simply do not exist elsewhere in the fleet. She is also bigger, which means more choice but also more people. Older Princess ships are smaller and can feel more intimate, and some sail itineraries or regions Sun Princess does not.

Feature	Sun Princess (Sphere class)	Older Princess ships
Size and guest count	Largest in the fleet, about 4,300 guests	Smaller, more intimate scale
Signature top-deck space	The Dome (glass, pool by day, Cirque Éloize by night)	Traditional enclosed lounges
Atrium	Three-deck Piazza with outward suspended Sphere and movable LED screen	Interior-facing Piazza
Adults-only retreat	Expanded Sanctuary Collection with suites, private deck and pool	Standard Sanctuary sun retreat
Propulsion	Dual-fuel LNG, newest systems	Conventional

The newness advantage is real: Sun Princess is the freshest, most advanced ship Princess sails, so pairing her with a region like the Mediterranean means the very latest design alongside the region’s timeless treasures. If your priority is the ship itself, Sphere class wins clearly. If your priority is a specific itinerary an older ship happens to sail, weigh that against the design leap.

Best spots aboard: a quick playbook

Once you understand the layout, using the ship well comes down to matching the space to the moment. A few reliable calls:

• Best morning coffee: the International Café by the Piazza, open 24 hours, with the atrium waking up around you.
• Best quiet sun on a sea day: the aft wake-view pool, or the Sanctuary Collection deck if you have access.
• Best light-filled swim: The Dome early in the day, before the midday crowd and before the evening show reset.
• Best seat for live entertainment: a low table near the movable LED screen in the Piazza, or an upper balcony for the wider view.
• Best evening under the sky: Movies Under the Stars on the main pool deck on a warm night.
• Best special dinner with a view: Love by Britto or The Catch by Rudi for the wake-view specialty experience.

Quiet retreats and where to watch shows

Big ships reward guests who learn where the calm is. On Sun Princess, the quiet layers stack up: the Sanctuary Collection is the dedicated adults-only retreat, the upper Piazza balconies are peaceful outside performance times, and the aft decks away from the main pool stay calmer through the day. Early mornings anywhere on the open decks belong to the few who are up, and port days empty the ship out for anyone who chooses to stay aboard.

For shows, the ship gives you three main stages, each with its own character. The Princess Theater is the main house for production shows, Princess Live is the smaller, more intimate venue, and The Dome hosts the Cirque Éloize acrobatic performances against its glass shell. The Piazza’s movable LED screen adds a fourth, more casual layer of live entertainment woven through the day. Check the schedule in the Princess app each morning, note the show times, and arrive early for the Dome and the Princess Theater on nights with headline performances, since those fill fastest. Balancing marquee ports with these evenings aboard is part of the art of the trip; our overview of the Mediterranean and Greek Isles season shows how the ship days and shore days fit together.

Choosing a cabin on Sun Princess

The cabin categories run from Interior and Oceanview through Balcony, which makes up a large share of the ship, to Mini-Suites and the Sanctuary Collection suites with retreat access. On a warm, scenic Mediterranean itinerary a Balcony is lovely for sail-ins and warm evenings, though the honest truth on a port-heavy voyage is that you spend less time in the cabin than you would on a relaxed scenic cruise, so weigh the balcony against how much you will actually use it.

For value, an Interior or a sheltered Balcony does the job. The best all-round choice is a midship Balcony on the mid-decks, which gives you light, space and the steadiest ride. The top of the range is a Sanctuary Collection suite, which folds the private retreat into the room. When you look at the deck plan, avoid cabins directly under the pool deck, the buffet or the Dome for noise, rooms near nightlife venues, forward high-deck rooms if anyone in your party is prone to motion, and lower-deck balconies with obstructed or lifeboat-blocked views. A few minutes on the deck plan pays off for the whole voyage.

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Get the complete Sun Princess playbook

For a deck-by-deck breakdown of every space on this guide, plus cabin picks, dining strategy and MedallionClass setup, read “The Ultimate Guide to Sailing on Sun Princess.” It is part of the Ultimate Ship Guides series by Leo Sotropa, with clear action steps in every chapter so you board knowing exactly how to use the ship.

Frequently asked questions

What is Sphere class and how is Sun Princess different from older Princess ships?

Sphere class is Princess’s newest and largest ship design, a clean-sheet redesign built to feel light, airy and connected to the sea, and the line’s first dual-fuel LNG vessels. Sun Princess is the first of the class. Compared with older Princess ships she is bigger, about 4,300 guests across 21 decks, with more glass, the newest technology, and signature spaces like The Dome and the outward suspended Sphere that do not exist elsewhere in the fleet.

What is The Dome on Sun Princess?

The Dome is a geodesic glass-enclosed structure at the top of the ship, inspired by Santorini’s terraces. By day it is an indoor-outdoor pool retreat filled with light, and by night it becomes a theater staging Cirque Éloize acrobatic shows. Go early in the day for a calm swim, and check show times in the Princess app if you want an evening performance, since seats fill quickly.

What is the Sphere in the Piazza?

The Piazza on Sun Princess is a reimagined three-deck atrium hub, and the Sphere is an outward, glass-walled structure suspended off the side of the ship that gives expansive ocean views from what used to be an interior space. The Piazza also has a movable LED screen for live entertainment, so the atrium doubles as a performance venue through the day.

What is the Sanctuary Collection?

The Sanctuary Collection is an adults-only retreat and an expanded suite-and-retreat concept with a private sun deck, pool and exclusive dining. Book a Sanctuary Collection suite and the retreat access comes with the room; otherwise check the Princess app for day access or passes, as availability varies. It is the ship’s dedicated calm space away from the main crowds.

Where are the best quiet spots on Sun Princess?

The Sanctuary Collection is the dedicated adults-only retreat. Beyond that, the aft wake-view pool and the upper-deck edges away from the main Sea Breeze pool stay calmer, the upper Piazza balconies are peaceful outside performance times, and port days empty the ship for anyone who stays aboard. Early mornings on the open decks are quiet almost everywhere.

Where should I watch shows on Sun Princess?

There are three main stages: the Princess Theater for production shows, the smaller Princess Live, and The Dome for Cirque Éloize acrobatics. The Piazza’s movable LED screen adds casual live entertainment through the day, and Movies Under the Stars plays films on the poolside LED screen. Check the schedule in the Princess app each morning and arrive early for the Dome and the Princess Theater on headline nights.

Which cabin should I book on Sun Princess?

For value, an Interior or sheltered Balcony works well. The best all-round choice is a midship Balcony on the mid-decks for light, space and the steadiest ride, and the top of the range is a Sanctuary Collection suite. Check the deck plan and avoid cabins under the pool deck, buffet or Dome, rooms near nightlife, forward high-deck rooms if you are prone to motion, and lower-deck balconies with obstructed views. For more, see our Sun Princess tips.