German cruise line, TUI Cruises has ordered two new Mein Schiff class cruise ships to operate in Europe.

The new ships will be delivered in 2016 and 2017.

TUI Cruises, which is a joint venture between TUI AG and Royal Caribbean, currently has three ships in its fleet, with a fourth being built for service in 2015.

The new ships will be sister ships and will be called Mein Schiff 5 and Mein Schiff 6.

They will have 15 decks and carry 2,500 passengers in 1,250 cabins.

Ninety percent of cabins will be outside and 82 percent will have balconies.

TUI AG chief executive Friedrich Joussen said extra ships will meet rising demand for European cruising.

“The boats are most congested as the business grows,” he said.

“TUI Cruises and their ships are thus a crucial pillar for the differentiation and growth strategy of the TUI Group.”

Further details including features and itineraries will be released closer to the launch dates.

In June, the line launched Mein Schiff 3, its first newbuild vessel. According to Joussen, bookings on the new ship were almost sold out before it set sails on 12 June.

TUI’s first two ships – Mein Schiff 1 and Mein Schiff 2 – were part of the Celebrity Cruises fleet before they were renovated for the TUI line.