Hạ Long Bay is a UNESCO World Heritage Site and popular travel destination in Quảng Ninh Province, Vietnam.  It receives significant sediment and pollutant loads from the Bach Dong River and smaller rivers discharging directly into the bay.  It has numerous industry and urban areas along its length raising interest among researchers, industry and the environmental regulatory community.

The bay features thousands of limestone karsts and isles in various shapes and sizes. Hạ Long Bay is a center of a larger zone which includes Bái Tử Long Bay to the northeast, and Cát Bà Island to the southwest. These larger zones share a similar geological, geographical, geomorphological, climate and cultural characters.

Hạ Long Bay has an area of approximately 1,553 square kilometers, including almost 2,000 islets, most of which are limestone. The core of the bay has an area of 334 square kilometers with a high density of 775 islets (Wikipedia).

This model grid contains 13,342 cells, with an average orthogonal deviation of 0.02 degrees. The grid stretches from sea coast of Halong city of Quang Ninh province of Vietnam to the sea. This grid was built in multiple stages and then joined to together to make one complete grid using EFDC+ Explorer and Grid+.