Such a prison would be surrounded by the swamp with no way off except by barge and boats (or helicopters).
And maybe daily the guards would feed the alligators something like catfish, chicken or whatever. The prisoners could watch...
Never been to Angola, have you? My dad worked there as a guard for a while when jobs were scarce (sixty years ago). Your description is a good match. Admittedly, it isn't a wildlife refuge, but the rest is pretty accurate.
I have always liked the idea of putting prisoners in an island with no way to leave and no visitors. It would be a life sentence. No one of the opposite sex. The only people you see are other prisoners. BIG MOSQUITO prison sounds like a nice alternative. No need to build expensive prisons.