This is a fun trip. It doesn't take long, but you can always reverse the route, and then play about in Birkwith Cave or Calf Holes afterwards to make it a full day's caving. Water levels should be reasonable - there are canals to be passed that could be awkward in high water, and there is a waterfall to negotiate. The place also shouldn't be flooded with novices. It would be easy for an inexperienced person to get into difficulties, and as some of the route is strictly single file, it wouldn't always be straightforward to get help to them. Assuming normal water levels, it shouldn't be necessary to get even your feet wet, but as the ancient fixed lines used to keep dry in the canals are belayed to rotting anchors, one should be prepared for an unscheduled wetting. No SRT equipment is required, although 10 metres of 8 mm handline may come in useful if you have any novices with you.
This description starts from the Dismal Hill end and goes upstream to emerge from Old Ing, for no other reason than Dismal Hill is the first entrance you come to, and if you do decide to reverse the route, you don't have so far to walk back to the car.
Dismal Hill Cave has two entrances. The originally one that was traditionally a ladder route, and the more recent one that is an SRT route. The former is more fun, and so that is assumed. To find it from the car park, follow the track behind the Birkwith wooded area. It goes through a gate, and 350 metres beyond this you will see a small stake sticking up about 20 metres to the right of the track. That marks the new entrance. The old entrance is about 20 metres on the other side of the track in a rocky shake-hole.
A short flat-crawl leads out onto a short drop, easily negotiated. The next drop descends a flake, and although it looks disconcerting from the top, there are some hidden footholds near the bottom which makes it reasonably straightforward. At the bottom a thrutch over some boulders along the rift leads into a sub-parallel rift. The easiest way from here is to go back up the parallel rift, and identify a low passage off to the right. This leads into a wide bedding, which is a bit awkward and puddly, but after a few minutes it drops into the main Dismal Hill stream passage, which contains the combined flows of Old Ing Cave and Red Moss Pot.
There is some entertaining caving to be had by visiting the downstream sump, most of which is traversed. At one point the route passes under an aven with a fragment of a rotting electron ladder abandoned at the base. Eventually, you reach a point where you can peer along a low canal, which is as far as is practical (without getting wet).
Returning upstream, a short section of canal is easily passed using a fixed line, at the end of which the pitch from the new entrance lands on a shelf on the right. A second short section of canal is again passed using a fixed rope (with one of the bolts pulled out!) to a short blasted crawl which bypasses the first sump. On the far side of this is yet another fixed line traverse. This starts with a somewhat ominous air and is a little confined, but after a few metres the passage opens up again, and much of the rest of the traverse can be comfortably bridged. The rope finishes where a couple of bits of metal enable an ascent of the left-hand wall into a bedding passage. This bypasses a deep bit of water, and emerges into the impressive Swift Falls Chamber where the water cascades down a fine waterfall. This is easily free-climbed in normal conditions, but a fixed rope can be used to aid the ascent in wetter conditions, although it should be noted that both the rope and the belays are well past their sell-by date.
Above the waterfall a pleasant length of passage leads to the start of the Leeds and Liverpool Canal, a chilly swim best left alone, at the end of which are the two short sumps through to Old Ing. These are bypassed using Mick's End, a short bedding passage. Returning downstream, Mick's End may be found high up on the true right. An easy climb enters a crawl some of which is floored with bang debris. This becomes flat-out shortly before it pops out in the roof of Old Ing. The passage downstream can be followed to the other side of the sumps, and the entrance is ten minutes caving upstream. If you are prepared to get wet, the lengthy Rough Hill Inlet is worth exploring. It enters on the right at a corner 100 m upstream of Mick's End.