Pluto may have a 60 mile deep liquid water ocean
 

We used to think of Pluto a remote frigid rock, but since the New Horizons visit, it's vying for the title of the solar system's most interesting (ex-) planet. An earlier study showed that its core is warm enough to support a liquid water ocean, and...

https://www.engadget.com/2016/09/26/...d-water-ocean/