島悦子 (Etsuko Shima), age 51, is a pool and open water swimmer from Japan who successfully crossed the Tsugaru Channel from Honshu to Hokkaido in 9 hours 38 minutes on 23 July 2012 under the helm of Captain Mizushima with Masayuki Moriya as Observer. She swam with 小林功司 (Kouji Kobayashi), 斎藤好豪 (Saito Yoshitaka), 斎藤直子 (Naoko Saito), 横田美歩子 (Mihoko Yokota), and 大内龍平 (Ryuhei Ouchi).
She also completed a crossing of the Tsugaru Channel in Japan on 16 July 2014 in 9 hours 19 minutes together with Okuda Yumiko (奥田由美子（おくだ ゆみこ), Kawasaki Noriko (河崎典子（かわさき のりこ), Shima Akira (島晃（しま あきら), Morita Shinya (森田伸也（もりた しんや), and Yamamoto Takeshi (山本毅（やまもと たけし).
She was a member of the Ocean Navi relay team that took 16 hours 18 minutes to swim across the 43 km Sado Channel course. The Ocean Navi team included Masayuki Moriya, Motoko Honma, Hidehiko Kato, Kaori Fukusima, Noriko Kawasaki, Ayako Kawasaki, Yoshimitsu Kitazawa, Noriko Kimura, Jun Kuwabara, Kumiko Koizumi, Maki Sakamoto, Akira Shima, Etsuko Shima, Akiko Niide, Isami Mitsuhashi, Kyoko Morikawa, and Eriko Yoshino.