Royal Caribbean International today marked a dual milestone for its two new Quantum Class ships.

Quantum of the Seas, scheduled to be delivered in autumn 2014, received its first block as a keel was lowered and put into place today in Papenburg, Germany.

Sister-ship Anthem of the Seas had its first piece of steel cut today, signalling the first step in the ship’s construction.

Adam Goldstein, president and chief executive of Royal Caribbean International, said: “Today is a very special day in the development of our new Quantum class, as we are now two steps closer to delighting guests around the world with Quantum cruising.

“It’s incredibly rewarding to see Quantum of the Seas and Anthem of the Seas coming together so well, and today we not only honour these two very important milestones, but also recognise the years of hard work and dedication from the team developing these ships.”

During the keel laying ceremony for Quantum of the Seas, newly minted coins were placed under the keel which then stays in place until the end of construction. Once the ship is nearing completion the coins are retrieved and presented to the ship’s Captain and crew to be placed onboard the ship.

According to maritime tradition, the coins are said to bring luck to the ship during its construction and then to its Captain and crew when out to sea.

The cruise line said the Quantum class ships will feature the first skydiving experience at sea, bumper cars, roller skating and the North Star which will transport guests more than 300ft above the ocean.

Anthem of the Seas will debut in spring 2015.