The Kalmius () is one of two rivers flowing through the Ukrainian city of Mariupol. The other river called the Kalchik flows into the Kalmius. The Kalmius flows into the Sea of Azov near the Azovstal steel manufacturing combine.

Kalmius was apparently also the name of a 16th century Cossack fortress.

Rivers of Ukraine

Кальмиус (река) | Кальміус | Kalmius