First, one must conduct the steps necessary to make the Alaskan pipeline viable (shit in a condom, freeze it).
The Underwater Volcano is when a female voraciously pleasures herself with an Alaskan Pipeline whilst in the bathtub and on her period.
Created by A. UoS 2015.
Dan: Hey Mary, fancy fucking later?
Mary: Sorry Dan, I'm on my period! I think I'll just give the Underwater Volcano a try tonight
Dan: No problem, I've heard the Underwater Volcano is a fantastic experience, enjoy!