I'll echo that. From what I remember, it is dangerously floodprone.
In other words, if you got caught in there by a rise in water levels, you would be unlikely to survive.
It comprises several hundred metres of crawling, much of it flat out. Along the way are several dome shapes chambers where you can stand up. These have clear tide-marks at chest height, so if you were lucky enough not to drown in the crawls then you would freeze to death standing in chest deep water.
Don't let this put you off, just choose a dry settled day for your trip. Enjoy.