Dibar Dighi, Historic water tank in Patnitala Upazila, Bangladesh.

Dibar Dighi is a historic water tank in Patnitala Upazila with a granite octagonal pillar rising from its center. The pillar features three circular rings and a crown-like top, surrounded by a large expanse of water.

The tank and pillar are not precisely dated. Scholars link them to Dibyak (also Divyak), a Kaivarta vassal who defeated his 11th-century Pala overlord Mahipala II; R. C. Majumdar read this as a local samanta's rebellion, Ram Sharan Sharma as a peasant revolt. Construction may have been carried out under Dibyak, his brother Rudak or his nephew Bhim. In 1939 the Central Government declared the site a heritage site.

Locals call the tank Karmakarer Jalasay, "the Karmakar's water body", and the village name Dibar is traced to King Dibyak. A legend says a jinn dug the lake in a single night. The octagonal granite pillar in the middle is known as Kaivarta Stambha, after the Kaivarta chief.

The area is maintained by the Rajshahi Social Forestry Division and features a mini-zoo and forest surrounding the water tank. Visitors can take boat rides across the water to explore the site.

Alexander Cunningham never visited the tank himself: his servant surveyed it in 1879–80, and Cunningham regretted that such a large single-shaft stone pillar had not been recorded in the subcontinent since Ashoka's reign. Francis Buchanan-Hamilton had measured it in 1807–08 at 22.5 cubits high.