Water End Swallow Holes is a biological site of Special Scientific Interest in Hertfordshire, south-east England.

Located in Welham Green and under the planning authority of Welwyn Hatfield District Council, it has an area of 11.3 hectares (28 acres).

[1][2] The site covers more than fifteen swallet holes, the only ones in chalk which are a permanent feature of the landscape.

Next to the holes is a swamp area of willow carr which is biologically important, and in deep water there is reed sweet-grass.

[1] From the sinkholes the waters become the River Colne.