The construction of Royal Caribbean's first Icon Class cruise ship reached an important milestone this week when the keel was laid for Icon of the Seas.

At a ceremony held at the Meyer Turku shipyard in Finland, the official start of construction was celebrated.

Icon of the Seas will be the first of three Icon Class cruise ships, which the cruise line says will have a bold new design.  The cruise line has not yet released details on what the new ship looks like, or any of the features onboard.

Royal Caribbean Group President and CEO Jason Liberty was joined by Chairman Richard Fain, along with Meyer Turku senior executives and teams on Tuesday for the keel-laying.

The ship's keel is the first block, and it is maritime tradition to commemorate this phase of a new ship construction.  Icon's first block required a 3,000-ton crane lifting the block into place on top of freshly minted coins, which represent the shipyard and cruise line. 

The coins are meant to bring luck during construction, and they will be retrieved and given to Icon’s captain and crew before setting sail.

Royal Caribbean President and CEO Michael Bayley shared his excitement for the new ship, "Five years ago, we began dreaming of Icon of the Seas, and now the next phase of this iconic adventure is beginning."

"As this game-changing ship takes shape, the excitement from families and travelers alike, travel advisors and our partners continues to build. Later this year, we’ll reveal the lineup of firsts and favorites that will set a new standard for vacations come fall 2023."

Icon of the Seas will be powered by liquefied natural gas (LNG).

It's expected we will get more information on Icon of the Seas' deployment and ship details beginning later this spring.

Read more: A look at Royal Caribbean's plans now that cruises are back

There's been quite a lot of speculation as to what the sphere-like object spotted in the shipyard building Royal Caribbean's new cruise ship might be, and today we have new photos to share of it.

I posted yesterday an exclusive photo from the shipyard constructing Icon of the Seas a large pearl-shaped object that is unlike anything we've seen on a Royal Caribbean ship prior to this point.

Since posting that photo, more photos have emerged of the construction of this object.

Ruslan shared close-up photos of the object, including a look at its construction prior to the photo shared yesterday.

What could it be?

After posting the photo yesterday, Royal Caribbean International President and CEO Michael Bayley shared a link to the article on his Facebook page with the question everyone wants to know, "Hmmmmm what could this iconic thing be?"

There has been quite a lot of guesses shared on social media as to what this might be, and I'm not sure there's any clear consensus yet.

One of the most frequently guessed ideas is that it is a tank for the ship's liquefied natural gas (LNG).

Icon of the Seas will be the first Royal Caribbean cruise ship to be powered by LNG, but Royal Caribbean shared an update back in October 2021 that the LNG tanks had already been installed. Plus, those tanks look substantially larger than this sphere object.

There have been lots of other guesses (some serious, and some not) for what it might be, including:

• Gyroscope
• Next-gen bungee jump experience
• Repurposed alien spacecraft from Area 51
• Planetarium
• IMAX Theater

Whatever it ends up being, we'll have to wait for Royal Caribbean to reveal it at a later date.

Icon of the Seas will be the first ship in the Icon Class to launch.  She is scheduled to be delivered in Fall 2023, and there are two other Icon Class ships on order.

The other two ships will be delivered in 2025 and 2026.

Royal Caribbean has been quiet about its next new class of cruise ship, but it looks like we're starting to get our first look at construction taking place, including something that I have no idea what it could be.

Ship blocks for construction of Royal Caribbean's Icon of the Seas arrived recently to the Meyer Turku shipyard in Finland.

Tug boats brought these giant pieces of what will become the hull of Icon of the Seas to the shipyard so that they can be joined together.

Janne-Petteri Kumpulainen shared photos of the pre-assembled blocks being brought in on a snowy day.

Cruise ships are built in a module process, where engineers break down the ship into smaller pieces that they later assemble. The reason ships are built in this manner is so that different engineers and specialists can work simultaneously, which cuts down on overall construction time.

Once the blocks arrive at the shipyard, they will be joined and welded together.

In addition to Janne's photos, a source that wishes to remain anonymous sent in a photo from the shipyard of a large pearl-shaped object that is destined for Icon of the Seas.

What is it? Your guess is as good as mine. Share your guesses in the comments!

Over the past years, Royal Caribbean has looked to distinguish each new class of ship with an attention grabbing feature that instantly draws the attention of the public. The Ultimate Abyss, North Star, and Central Park are just some examples of signature features onboard.

Perhaps this dome is part of something completely different for Royal Caribbean.

Royal Caribbean has hinted at Icon of the Seas being a "game changer" new ship for the cruise line.

Back in April 2021, Royal Caribbean International President and CEO Michael Bayley talked briefly about the new ship, "We have the brand new Icon class coming, which is going to be a real game changer."

"When you think about what a game changer Oasis class was and is, Icon is the next generation the evolution of Oasis."

Not much else is known about the Icon Class, but according to Royal Caribbean Group SEC filings in April 2021, the unnamed Icon Class ships will have a capacity of approximately 5,600 passengers.

Each ship will be powered by a combination of liquefied natural gas (LNG) and fuel cell technology.

Icon of the Seas is scheduled for deliver in the third quarter of 2023.

Royal Caribbean posted a new video update with the progress being made on the cruise line's next generation cruise ship.

Icon of the Seas is under construction at the Meyer Turku shipyard in Finland, and we have a closer look at  how the ship will be powered by liquefied natural gas (LNG).

This will be the first Royal Caribbean cruise ship to be powered by LNG.

Traditionally, cruise ships are powered by diesel. The advantage LNG has over diesel is it is more energy-efficient and will reduce fuel consumption and emissions.

LNG is considered to be the cleanest-burning fossil fuel available because it has virtually zero sulfur dioxides and particulates, and a significant reduction in nitrous oxides.

Royal Caribbean's overall goal is to become emission-free.

The LNG fuel tank is 307 tons and 90 feet long, and were installed recently into one of the blocks that makes up the new ship. Royal Caribbean says the two LNG fuel takes are the largest in the cruise industry.

In addition, Icon of the Seas will utilize a shore power connection that removes emissions while connected at port.

Icon will have advanced waste heat recovery systems that repurpose heat to be used as energy across the ship.

Additional details about Icon of the Seas largely remain unknown. Royal Caribbean promises, " it will make waves with a mix of innovations and adventures cruising’s never seen before."

According to Royal Caribbean Group SEC filings in April 2021, the unnamed Icon Class ships will have a capacity of approximately 5,600 passengers.

The first of the revolutionary Icon Class is set to make its debut in fall 2023, and two other Icon Class ships are on order. The other two ships will be delivered in 2025 and 2026.

Royal Caribbean announced the official start of construction for its newest cruise ship, along with its name.

On June 14, construction officially began on the first Icon Class cruise ship with a steel cutting ceremony at the Meyer Turku shipyard in Finland, which is the same shipyard that built a number of Royal Caribbean ship, including Allure and Oasis of the Seas.

Royal Caribbean also confirmed the ship's name will be Icon of the Seas.

The Icon Class ships will be Royal Caribbean's newest class of cruise ships.

Debuting in fall 2023, Icon will be the cruise line’s first of three ships to be powered by LNG (liquefied natural gas). LNG and the state-of-the-art ship’s additional environmentally friendly applications, such as shore power connection, will boost energy efficiencies and reduce carbon footprint. More details about Icon’s advanced environmental technologies will be revealed at a future date.

Not much else is known about the Icon Class, but according to Royal Caribbean Group SEC filings in April 2021, the unnamed Icon Class ships will have a capacity of approximately 5,600 passengers.

This would make the Icon class ships larger than the Quantum Class ships, but slightly smaller than the Oasis Class ships.

There are three Icon Class ships on order:

• Unnamed first Icon class ship delivery in 3rd Quarter 2023
• Unnamed second Icon class ship delivery in 2nd Quarter 2025
• Unnamed third Icon class ship delivery in 2nd Quarter 2026

In attendance at the ceremony was Richard Fain, chairman and CEO, Royal Caribbean Group; Michael Bayley, president and CEO, Royal Caribbean International; and Tim Meyer, CEO of Meyer Turku.

“We made our commitment to making clean power at sea a reality – and soon the norm – when Icon Class was first announced in 2016, and we’re excited to see construction underway on what will truly be a ship unlike any other,” said Michael Bayley, president and CEO, Royal Caribbean International. “Our decades of work in ocean conservation, energy efficiency and continuous improvement will be evident all throughout Icon. We look forward to revealing more of the game-changing features our guests and crew have in store as she begins to take shape.”