The Gulf of Martaban (Burmese: မုတ္တမပင်လယ်ကွေ့) is an arm of the Andaman Sea in the southern part of Burma. The gulf is named after the port city of Mottama (formerly known as Martaban). The Salween Sittaung and Yangon rivers empty into it.
A characteristic feature of the Gulf of Martaban is that it has a tide-dominated coastline. Tides ranges between 4–7 m with the highest tidal range at the Elephant Point in the western Gulf of Martaban.
During spring tide, when the tidal range is around 6.6 m, the turbid zone covers an area of more than 45,000 sq km making it one of the largest perennially turbid zones of the world's oceans. During neap tide, with tidal range of 2.98 m, the highly turbid zone coverage drops to 15,000 sq km. The edge of the highly turbid zone migrates back-and-forth in-sync with every tidal cycle by nearly 150 km.