User blog comment:SigmaAlphaThree/100 Questions for the traitor Arkanov/@comment-7270135-20160103232532/@comment-7270135-20160116023002

Probably, but instead it would be bending the water around her into a bubble instead of making a water bubble like she uses to help fish be mobile outside their ponds and stuff. Though she might just cast that spell that allows you to breathe underwater for a short time.

It's entirely possible! I think you just have to be a bit skilled to do it, and besides River isn't super tiny so he could easily do it without bending his back too much. He would just need to be really close to her, and her hips probably angled towards him.