Depends upon the characteristics. Aquifers are typically very, very large (its late and descriptions just aren't coming very well for me tonight) that take up the entire (for the most part) of the space in the cavern. Anything else is labelled the same as you would find on the surface. Lakes, streams, rivers (very rare and most are labelled simply as rapids), and waterfalls all have the same prefixes that you would find topside. Sumps are unique to the underground in which the lake/pond/pool comes up to the ceiling leaving no airspace. They will coninue on in one fashion or another. If its just a short little distance (read: bodylength or less) with an airpocket on the other side, its called an ear dip and some fellow cavers even call it fun.😀 How long can you hold your breath and still be able to physically exert yourself to get through a crawlway?
For more info, check out a good book on Karst. I'd suggets the one by Dr. William White (I can't think of the name of the book right now. PM me if you are interested in the name.)