Sir Creek (/sər ˈkrik/ ⓘ sər KREEK), originally Ban Ganga,[1] is a 96 km (60 mi) tidal estuary in the uninhabited marshlands of the Indus River Delta on the border between India and Pakistan.

These evershifting creeks exit Indian territory, enter Pakistan, re-enter India, and vice versa, creating a hard-to-patrol, marshy wetland border with no physical barrier or fencing.

The Bondho Dhoro channel, which enters India further north of Harami Nala in the Sujawal District of Sindh province of Pakistan, is another potential point of infiltration by boat.

In 1968, an international tribunal resolved the larger Great Rann of Kutch border claims of India and Pakistan, which also covered Sir Creek.

Since neither side has conceded ground, India has proposed that the maritime boundary could be demarcated first, as per the provisions of Technical Aspects of Law of Sea (TALOS).

Paragraph 9 of the verdict states that the border between Kutch and Sindh lies to the east of Sir Creek, whereas paragraph 10 of the verdict further qualifies that "since Sir Creek is navigable most of the year, according to international law and the thalweg principle, a boundary can only be fixed in the middle of the navigable channel, which meant that it has been divided between Sindh and Kutch, and thereby India and Pakistan.

[14] When the thalweg principle is applied, the UNCLOS (United Nations Convention on the Law of the Sea) supports India's position, which "would result in the shifting of the land/sea terminus point several kilometres to the detriment of Pakistan, leading in turn to a loss of several thousand square kilometres of its Exclusive Economic Zone under the United Nations Convention on Law of the Sea.

[11] Though Pakistan does not dispute the 1925 map, it maintains that the doctrine is not applicable in this case as it most commonly applies to non-tidal rivers, and Sir Creek is a tidal estuary.

If the boundary line is demarcated according to the thalweg principle applied to the current channel, Pakistan and India would both lose small amounts of wetland territory that were historically part of their provinces.

Much of the region is rich in oil and gas below the sea bed, and control over the creek would have a huge bearing on the energy potential of each nation.

UN law advocates a minimum penalty for this offense and release of boats, but the governments of India and Pakistan catch these fishers and keep them in prisons for a long time.

Their release happens through the land boundary of India and Pakistan (Wagha border), so these fishers return to their home country without their boats.

[15] Pakistan built the LBOD canal between 1987 and 1997 to collect agricultural saline water and industrial effluents generated in the area around the main Indus river.

However, the LBOD construction is in violation of the Indus Waters Treaty (Article IV), causing material damage (i.e. inundating the creek area exposed during the low tide) to India.

[19] From June 2019, several newspapers reported that Pakistan had rapidly built up forces at Sir Creek, and India swiftly responded likewise.

Pakistan has also set up two new marine posts west of Pir Samadhi Creek in the area of Bandha Dhora and Harami Dhoro.

[6] On 9 September 2019, after abandoned boats were found by the Indian Army in Sir Creek, India issued an alert regarding a potential terror attack.