turtles are cool. You keep them in a fishtank. They do smell, but we have a cover so it doesn't make a difference. The biggest issue is they're messy, and they need a big tank (they get up to 10 inch shells, and need about 10 gallon per inch)
This is a google pic. Mine's shells are about 5 inches right now. This one's about full grown. It's a boy, like my pair.
My tank's similar, but we don't bother aquatic plants. It's actually too small right now.