Cantão State Park, State park in Tocantins, Brazil.

Cantão State Park covers 90,018 hectares in Pium, Tocantins, bounded west by the Araguaia River and south by the Javaés River, which separates it from Araguaia National Park. Its flooded igapó forest lies in the ecotone between the Amazon rainforest and the Cerrado. The park holds 900 of the roughly 1,100 significant lakes of the middle Araguaia, and floods join them into one body of water for two to six months from October.

Cantão State Park was created by state law 996 of 14 July 1998, covering 88,928.88 hectares, with a deliberative council set up in the same law. Law 1,319 of 4 April 2002 redrew the boundaries to 90,017.89 hectares. The management plan was approved on 25 August 2005 and revised on 3 August 2016; by then the park was supported by the Amazon Region Protected Areas Program.

The park's name comes from the Cantão, the delta formed by the Javaés River, a black-water branch of the Araguaia, before it joins the main channel past Ilha do Bananal. The flooded forests and lakes hold species of both the Cerrado and the Amazon, and the park runs educational activities such as lectures, workshops, training courses, video shows and monitored trails.

The site is accessible through local guides who offer tours of the grounds and help visitors find the best routes. It is wise to prepare for changing conditions, as the landscape varies greatly depending on the season.

The Cantão holds 900 of the roughly 1,100 sizable lakes of the middle Araguaia. When the floods recede, many stay isolated and become nurseries where fish feed and breed, and preferred habitat for giant otters and black caimans.