Tanguar Haor (Bengali: টাঙ্গুয়ার হাওর), located in the Dharmapasha and Tahirpur upazilas of Sunamganj District in Bangladesh, is a unique wetland ecosystem of national importance and has come into international focus. The area of Tanguar Haor including 46 villages within the haor is about 100 square kilometres (39 sq mi) of which 2,802.36 ha is wetland. It is the source of livelihood for more than 40,000 people. Bangladesh declared it an Ecologically Critical Area in 1999 considering its critical condition as a result of overexploitation of its natural resources.

Every winter the haor is home to about 200 types of migratory birds. In 1999–2000, the government earned 7,073,184 takas as revenue just from fisheries of the haor. There are more than 140 species of fresh water fish in the haor. The more predominant among them are: ayir, Cat fish, baim, tara, gutum, gulsha, tengra, titna, garia, beti, kakia. Gulli, balua, ban tulsi, nalkhagra and other freshwater wetland trees are in this haor.

Plant species like Hizol (Barringtonia acutangula), Clematis cadmia, Crataeva nurvala, Euryale ferox, Nelumbo nucifera, Ottelia alismoides, Oxystelma secamone var. secamone, Pongamia pinnata, Rosa clinophylla, and Typha species are present.

It has become more popular with tourists as a tourist attraction due to the number of houseboats plying at Tanguar Haor. There is a big houseboat in Tanguar Haor. It is a huge, slow-moving barges used for leisure trips. This service is inspired from the houseboat Rabindranath Tagore used during his visit to Shilaidaha. It is in service from since 2021. It is about 71 feet (22 m) long and about 14 feet (4.3 m) wide at the middle.

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  A small village at Tanguar haor
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  Sunset
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  A tourist houseboat in Tanguar Haor

25°09′N 91°04′E / 25.150°N 91.067°E / 25.150; 91.067