what is a narrow arm of the sea at the mouth of a river where the ocean tide meets the river current called?

this article will tell you.

http://www.whoi.edu/oceanus/viewArticle.do?id=2486

The narrow arm of the sea at the mouth of a river where the ocean tide meets the river current is called an estuary. To find this answer, you can start by conducting a simple online search using keywords such as "narrow arm of the sea at river mouth" or "river mouth where tide meets river current." This will bring up various sources, including definitions and descriptions of estuaries. Additionally, you can refer to geography or oceanography textbooks, which often explain the concept of estuaries in detail.