If my snakes are inside I either hold them or I put them on something like the stair railing to climb, and I stay right by them.
When the weather is nice enough to take them outside they get to crawl around in the grass or in a small/young tree that is short enough I can still reach to the top if I need to get the snake out of it.
I also have a kiddie/wading pool that the snakes can use for swimming in shallow water. Some like that better than others.