In 1998, a 4-year old girl broke into a frozen pond in Austria [0]. She was found at the bottom of the lake after 30 minutes, with a body temperature of around 18 °C (so much higher than the case described in the article). She made a complete and full recovery (her story was filmed) and afaik lives a completely normal life as an adult now.

[0] https://www.kleinezeitung.at/artikel/3915285/Kaerntner-Wunde...