If you love cruises and the idea of living out the rest of your days on a luxury megaship sounds like paradise, you'll want to start saving up for 2025.

That's when Miami-based residential shipbuilder Storylines plans to launch its new 753-foot megaship filled with 547 private residences that it says will bring in an estimated $1.5 billion in sales. Storylines bills the cruise ship, called the MV Narrative, as "the world's first environmentally sustainable private residence ship."

The residences, which range in size from 237 to 1,970 square feet, are on sale now — and they aren't cheap. Storylines says the residences cost between $1 million and $8 million, with ownership lasting for the "lifetime of the vessel," which the company estimates as roughly 60 years.

For a shorter and cheaper buying opportunity, you can try to land one of the "limited number" of residences with 24-year leases that start at $647,000 for the total duration of the lease.

That's a lot more than you'd pay to go on a cruise vacation, but the ship's attraction is that you'll be able to "travel the world from the comfort of home," Storylines CEO Alister Punton said in a statement in August.

Storylines and Croatian shipyard Brodosplit are currently in the design-and-engineering phase of building the massive ship, which the companies say will be the first of its kind to be powered by liquid natural gas propulsion. The method lowers carbon emissions by about 25% compared with traditional diesel power.

The residences range from one- to four-bedroom living spaces, and most of them come with balconies to overlook the surrounding seas and various ports of call.

People who live on the MV Narrative will get to circumnavigate the globe every three years. Sailing from the ship's home port in Croatia, the ship will spend up to five days in major ports around the world. Sample itineraries on the Storylines website tout stops from the Mediterranean to Australia and South America.

In addition to the private luxury residences, the ship is set to offer 20 different restaurants and bars, a post office, a school, library, a hospital, a bank, office spaces and several pools.

Also included: a bowling alley, a micro-brewery, a movie theater, an open-air fitness deck with "racquet sports, yoga sun deck and running track" and a waterfront marina for personal watercrafts like jet skis and power boats.

The ship also boasts "the largest wellness center at sea," which includes a spa, gym and anti-aging clinic in a 10,000-square foot space.

In addition to the eco-conscious propulsion system, Storylines says the ship's focus on sustainability will include systems to convert waste into energy, while a "zero-waste farmer's market" will feature locally sourced products including produce grown in the solar-powered hydroponic garden.

If the thought of a life at sea does appeal to you — and you can afford it — you certainly won't be alone. Multiple other residence shipbuilders, like The World and Clydebuilt's Dark Island, are also selling luxury suites aboard megaships for people who want to live, or even retire, on the sea.

Those other units aren't any cheaper: The World's luxury suites range from $2 million to $15 million, and Clydebuilt's Dark Island has suites starting at $10.7 million.

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