Travelers who fantasize about owning a superyacht may be able to turn their dreams into reality — at a much lower price.

Residential yachts, as they are called, are essentially apartment buildings at sea. Buyers purchase apartments on massive yachts, rather than own and operate their own smaller vessels.

Once most of the apartments are sold, the yacht functions much like a luxury cruise line, and travels around the globe with onboard staff and access to restaurants, spas, wine cellars and gyms.

One residential yacht is Somnio, a 728-foot-long superyacht currently being built by the Norwegian shipbuilder Vard. It will be the world’s largest yacht once it’s completed in 2024, according to Vard’s website.

Somnio has 39 apartments, and prices start at 9.5 million euros ($11 million), said Erik Bredhe, Somnio’s co-founder and captain. Prices depend on the apartment’s size and location, with higher units costing more, he said.

While $11 million is more than enough to purchase a private yacht, it doesn’t get close to the cost of a superyacht.

Yacht influencer Denis Suka — known as “The Yacht Mogul” to his more than 550,000 Instagram followers — told CNBC he is helping to design a 295-foot superyacht called Mogul.

When completed, it will cost around $150 million with just one buyer, he said.

Somnio is more than twice the length of Mogul.

Total privacy isn’t necessarily what every yacht buyer wants, according to Bredhe. He said a major selling point of residential yachts is the ability to “mix with like-minded community members.”

“The single biggest factor is an intimate community with whom to share a truly global itinerary,” he told CNBC, adding that “the beauty of owning your own apartment is that you don’t have the worry of maintenance and planning that comes with your own yacht.”

The yacht’s staff will handle maintenance, repairs, fuel and food supplies, as well as shore tours, according to Somnio. Staff will also plan journey routes, though residents can recommend destinations too, according to the company’s website.

These don’t come free though. Buyers must pay an annual charge, which covers expenses related to maintenance, fuel, food and personal services, said Bredhe. There is, however, a “no tipping policy” on Somnio, he said, which can range from 15% to 20% of yacht charter costs.

Ownership on the boat is by invitation only, said Bredhe. Some buyers have directly approached the company while others have come from personal recommendations, he added.

Unlike most boats, residential yacht apartments may rise in value over time, said Bredhe.

This is true for another residential yacht named The World, which launched in 2002.

“All residence types have increased significantly in value since the ship’s launch, driven by demand from prospective buyers globally,” a company representative told CNBC.

Owners cannot, however, make money by renting out their apartments, though family members and guests can use the apartment if the owner is not onboard, said Bredhe.

At 644 feet long, The World has more than four times as many apartments as Somnio.

It has studios as well as one- to three-bedroom apartments ranging from $2 million to $15 million, a small number of which are currently for sale, a company representative told CNBC.

“When we saw The World sail into Rio de Janeiro and learned of its unique concept, we knew we had to be a part of it,” said a current resident who asked to remain anonymous to protect his privacy.

The resident has lived on the yacht for four years, during which time he explored Madagascar, Indonesia and the Mediterranean, he told CNBC.

“We like the carefree nature of being able to go to our home on The World whenever we like and only having to take hand luggage — as we have both summer and winter wardrobes aboard,” he said.

He said he never considered buying a private yacht because “our friends who have private yachts seem to have nothing but problems with either staff or mechanical issues, which seem to somewhat spoil their enjoyment.”

Since its launch, The World has traveled to places such as Greenland, the British Isles and the “White Continent” — Antarctica.

Another superyacht — the 948-foot-long Njord — is scheduled to be completed by 2025. It, too, is planning to sell apartments onboard to buyers who want the thrill of ocean travel without the responsibility of yacht ownership.