Hello,
I wouldnt put your snake in anything deeper than your waist, in the deepest point. Because you will need to get it out eventuly, and it might just go to the bottom and sit, well lay, and if it is a big green, it could stay under for quiet a while, if it wants. I also would not put it in something that is really big. They can get to a good speed in water, alot faster than on land, well you could be chasin it for hours, because what ever you want it to do, it will do the oppsiite, you want it out, it will stay in, and vise versa. And most important, if your green is not tame, I would not do it at all, because, I dont know you personally, but I am pretty sure you cant swim faster than a mad conda. You know if you have to go in to get it. you will deffinitly get bit, and if it is full grown, that would probibly not feel good. Just guessing
And if you decide to do it, personally I wouldnt, I dont see what good could come of it, I would have an extra person there, and if it is a biggin, maybe 2 extra people. Well that all I got.
Peace