Steam Ogre Issues
That’s an intermediary teleport location, if you go to the middle and jump up, you’ll teleport up to the platform where the champ is.
When you jump down into the pit, just above the water is a teleport zone which brings you to the platform above it with the champ. Lag can sometimes make you miss the teleport zone in the pit and you fall into water, jumping will let you hit the zone and get back up to the champ platform.
But that other part is definitely a bug, getting into there without a key.