Went with Andy W, to look at draining this passage. Water levels were low, extra neoprene was donned and then two hoods. Andy had been in first got to a low bit. This I managed to pass and got to a longer low section. This again was passed and passage turned another corner with the far end lacking any visible airspace. A strange noise was noted at the end, Andy confirmed the sound when he went for a second look thinking it was falling water but it sucking or blowing on air through a small gap. More work required here.