Twywell Gullet is a 17.1-hectare (42-acre) biological Site of Special Scientific Interest east of Kettering in Northamptonshire.

The site is in turn a small part of the former royal hunting Rockingham Forest.

[3] Twywell Gullet is a former ironstone quarry which has deep cuttings with steeply sloping banks.

It has species-rich limestone grassland on the slopes and ponds and scrub in the bottoms.

There are a number of uncommon ground nesting bees and wasps, and beetles include the nationally rare ruddy darter.