I'd be more concerned about the water pressure that deep, more than the water coming out. Someone going from Liminal straight to negative forty thousand feet'd get crushed.

Maybe Zouchouten or one of your demons could take it down there? I can make portals for random places to send them, but actually getting to Liminal without being caught or accused of being the spy is gonna be tricky. Especially if I'm taking the casket with me.