Carlton and Oulton Marshes is a 151 hectare nature reserve in Lowestoft in Suffolk.

[1] Carlton Marshes is part of the Sprat's Water and Marshes, Carlton Colville Site of Special Scientific Interest,[2] the Broadland Ramsar internationally important wetland site,[3][4] the Broadland Special Protection Area under the European Union Directive on the Conservation of Wild Birds,[5][6] and The Broads Special Area of Conservation.

Birds of prey include marsh harriers, barn owls and hobbies, and there are many wintering wildfowl and breeding waders.

Semi-aquatic fen raft spiders were released on the site in 2012 to boost the low British population, and underwater insectivorous bladderworts trap water fleas.

[1] The Angles Way footpath passes through Carlton Marsh south of Oulton Dyke, and Oulton Marsh north of the Dyke is also accessible by footpaths.