Add is being summoned to help so he is here now. Dynamo is waterproof and can navigate via motion/heat/electrical sensors, this is probably enough to get a better idea of what the pool "looks" like short of dragging Helena over to sonar it. Anything else of note that they can detect within the pool? Or is it just a regular pool with a deep end full of worm?

They're also gonna try and scoop up some worm samples, Dynamo can probably finagle a cup on their own... what kind of worms... how big... can we deploy a measuring stick or rod or w/e to try and touch the bottom of the Worm Layer, how deep do these worms go? Is there a bottom beneath the worm layer?