Kilijaarm / Chilia branch

The Chilia branch (Romanian: Brațul Chilia; Ukrainian: Кілійське гирло, romanized: Kiliiske hyrlo) is one of three main distributary channels of the river Danube that contribute to forming the Danube Delta. Lying at the northernmost area of the delta, the distributary creates a natural border between Romania and Ukraine (see Romania-Ukraine border) and is named after the two towns carrying the same name, located across from one another on both banks: Kiliia, on the northern, Ukrainian bank and Chilia Veche (Old Chilia) on the southern, Romanian bank.
The other two main branches of the Danube are the Sulina branch and the Sfântu Gheorghe branch.

Source: Wikipedia https://en.wikipedia.org/wiki/Chilia_branch