Their argument is that it is less polluting because people don't have to fly to have a tropical vacation. It seems to work, they are constantly expanding.
I went last December, the place was packed. Surprisingly I'd say about 40% of the guests were foreigners. It's nice but I don't know if I'd want to stay a whole week.
One of Germany's cargo airship projects. I'm pretty sure there have been more, but none got as far as Cargolifter (for cargo. For more modest ambitions, the Zeppelin NTs out of Bodensee are still going strong, 25 years on).
https://en.wikipedia.org/wiki/Tropical_Islands_Resort
(With rising energy costs, hopefully it can stay like this for a while)