The naval Battle of Ulsan, also known as the Battle of the Japanese Sea or Battle of the Korean Strait, took place on 14 August 1904 between cruiser squadrons of the Imperial Russian Navy and the Imperial Japanese Navy during the Russo-Japanese War, four days after the Battle of the Yellow Sea.

The Battle of the Yellow Sea was a major naval battle of the Russo-Japanese War, fought on 10 August 1904. In the Russian Navy, it was referred to as the Battle of 10 August. The battle foiled an attempt by the Russian fleet at Port Arthur to break out and form up with the Vladivostok squadron, forcing them to return to port. Four days later, the Battle off Ulsan similarly ended the Vladivostok group's sortie, forcing both fleets to remain at anchor.