Suggestions for finding volume

I have a model that has some tubing / voids.  I've attached a picture with highlighted blue area that characterizes the area I need to grab.  Are there any suggestions for how I can find the volume of the area?  Think of it like water filling into an area.  Some programs allow you to place a mark somewhere in the area and then the app goes out and finds the bounding constraints.  Is there anything similar in Grasshopper?