What kind of turtle are we talking about? If it is a larger species like the common red-eared slider of the pet trade it could outgrow the enclosure in time. You could create an enclosure with a large water portion along with a few basking areas made from driftwood anchored using expanding foam. I have seen entire underwater reef systems made from foam so it should hold up well.

Depending on the shape of the driftwood you could attach epiphytes like Bromeliads, Tillandsias, or Orchids as long as they are out of reach of the turtle. Turtles can be destructive and will trample plants. Any loose soil etc. will also get dragged into the water if you use it so it may be better to just go for the swamp look with driftwood/logs and skip land areas.

Aquatic plants will most likely get uprooted but if the turtle is small and you have appropriate lighting you could try some sturdy ones and see what happens. Floating plants like duckweed would look really nice, as would some of the larger floating plants.

I think the main issue would be the fact that the turtle would outgrow the enclosure unless you built it large from the start. Another concern is having a powerful filtration system to cope with the waste from the turtle.

I think you could design a great enclosure for a turtle if you took a little time to think about the possible problems that could occur and how to avoid them. Try doing a Google search for "turtle tanks" and look at photos as well as articles to see if others have made similar enclosures. Most people keep turtles in simplistic enclosures but there is no reason why you can't make yours a little habitat of its own.

Here is a link that might be useful: Turtle tank filtration

I found another good link, check out the basic turtle care and the section on water quality and filtration.

Here is a link that might be useful: Turtle care

I can tell you that it will not work in your typical set up! =) If you plan on keeping a turtle in a "terrarium" type set up you will have to make the background and substrate out of concrete (and have like "the best" filtrtion system you can get!) use a method similiar to the expanding foam method, and you will not be able to keep any kind of plants (except up high) or critters as the turtle will destroy/eat everything it can get to! Its in thier nature to dig! They will not stop, if they can get to it or get thier little claws into it they will destroy/eat it! Including expanding foam, I had a small (bout the size of a fifty cent piece) red ear slider that demolished a 70 gallon set up! not to mention they eat anything that moves! (or smells good!) he took some time but dug a hole right into the foam! (the little B@#$%&*!LOL!)Im not going to tell you what he did when he got bigger! So yeah....Be sure to make everything out of concrete and anchor everything thats going on the bottom securely! Keep live plants up high and good luck! =)

I think the best turtle species for naturalistic enclosures would be the bottom walking species like musk turtles, stinkpots, or mud turtles. Many of these turtles stay small and they do not require a basking area so you can dedicate the upper portion of the tank to plants as well as keeping floating plants.

Take a look at this link for images and sources for these turtles. Make sure to do your homework as these turtles have different requirements than red eared sliders and are not as easy to keep.

Here is a link that might be useful: Turtles

I had a painted box turtle a few years ago. A family member rescued it from a busy road. It loved my backyard (unfortunately, I had no available tanks at the time) until someone (the identity still remains a mystery today) opened the backyard gate and stole the turtle. I found the backyard gate open and couldn't locate the turle. I could understand how a turtle could get too big for a tank, though. I'm sure that you might need a large tank for a turtle (probably in the 70 gallon and up range). I looked at the links posted above and think that you should look at them, too. They certainly seem to know what they are talking about. Good luck with the turtle. What kind of turtle is it?