Maize Island Lagoon Conservation Park is a protected area in the Australian state of South Australia located in the locality of Holder about 155 kilometres (96 mi) north-east of the state capital of Adelaide and about 2 kilometres (1.2 mi) east of the Waikerie.

[1][3]: 1 The conservation park consists of the following land located on the southern side of the Murray River in the cadastral unit of the Hundred of Holder – sections 365, 427, 496, 497, 529 and 530.

The principal understorey species are Muehlenbeckia cunninghamii and Eremophila divaricata generally in low lying areas with Dodonaea angustissima and Acacia stenophylla forming tall shrublands on slightly higher ground.

A ground cover of introduced and native grasses is found in many areas.

The conservation park is classified as an IUCN Category III protected area.