I could be wrong, but I presume this, said to be the largest natural hole in Britain, was formed when the roof of a cave chamber collapsed. It's on the line of a fault, which probably helped.
Hull Pot is ~91 m (300' ) long by ~18 m (60' ) wide, and also ~18 m deep. There's no way down to the gravel-covered floor, except by abseiling or 'proper' climbing; I thought I'd spotted a few possibilities, but unfortunately not.
Quite a landmark, but be aware that it's a few hundred metres north of the main path – don't confuse it with Hunt Pot, a much narrower chasm nearly a kilometre away, which is on the path.