3rd try at posting--hope they all don't pop up at once--
Anyway regarding Costa Maya, just to clarify, Costa Maya is not a man made island. It's on the mainland of Mexico.Rumors have abounded that it was made by the cruise lines --each rumor had a different cruiseline developing it.
From what I've read and understand, it was a joint venture between the cruise lines, the Gov. and a group of investors. But, in a sense, aren't all the ports " Man-made "?
Look at St. Thomas--take out all the shopping mall like jewelry stores and what do you have left ?
I've been to Costa Maya several times--3 times before the hurricane wiped it off the earth about 2 years ago and once this past Jan. after it was re-opened as a port. Signs of the hurricane was very evident. The main shopping-port area is pretty much rebuilt, although there's a few things that were not rebuilt, like the ampi-theater that was in the middle of the shopping complex where they used to hold 2 Mexican folk dance shows daily. It won't be rebuilt. There's shops, a swimming pool in the middle of the complex, a couple of restaurants, etc. and of course, plenty of shops.
Down the coast a mile or 2 was a little village Mahajual ( spl ) that was a neat place to visit. Prior to the hurricane, it had a main street of dirt alongside the beach. Across the road were shops, a few bars, restaurants, etc. It was wiped off the planet too.
It's been mostly rebuilt. The dirt road has been replaced with a winding path of pavers--the shops are pretty much rebuilt . You can get cheap beachside massages, food, drinks, etc. You can swim, snorkel, etc. if that's your thing.
It's still a neat place to visit but the signs of the damage done to the natural environment is still evident and will be for years. You can get a cab or take a bus there from the main port complex--plenty of cabs available to take you back when you're ready to go.
I would say if you're looking for another St. Thomas, St. Martin or another Cozumel, you may not like Costa Maya. If you're looking for something different and wanting to get out and see some of the real Mexico, you would probably like it.