Nares Gladley Marsh is a 5.1-hectare (13-acre) Site of Special Scientific Interest north-west of Leighton Buzzard in Bedfordshire.

It was notified in 1990 under Section 28 of the Wildlife and Countryside Act 1981, and the local planning authority is Central Bedfordshire Council.

[1][2] The site is on the Lower Greensand in the valley of the River Ouzel.

It has marshland with a number of springs, and it has rich plant communities.

[1] The site is private land and there is no public access.