I've been in Stoke when the entrance was actually a whirlpool. It was our first visit there, so we hadn't seen it any other state. Good fun, and most exhillarating. The route to the sump, as I recall, only had a couple of inches of airspace. We were unsure of the route so spuddled around for a bit before retreating to the whirlpool. I seem to remember we were looking for the peeble crawl, but as everything was under water we failed to find it. Great fun when wet. Dank, dour and fetid when dry.