Yakov Yan Toumarkin (Hebrew: יעקב יאן טומרקין, Russian: Ян Я́ков Тума́ркин; born 15 February 1992) is a Russian-born Israeli Olympic backstroke swimmer.

[9] In July 2011, at the 2011 World Aquatics Championships in the 200-meter backstroke in Shanghai, China, he set a new Israeli long course (50 m) swimming record (1:58.21 minutes).

[2][10] Toumarkin said: "I managed to put all of the pressure out of my mind, and just pretended I was competing in a club competition in Israel.

[12] At the 2015 European Short Course Swimming Championships, he set the 100 IM Israeli national record with a time of 52.75.

[11] He swam for Israel at the 2017 Maccabiah Games, winning the men’s 200 m backstroke in a time of 2:00.17.