Ocean Sunrise

Tina, this is because textile is not stretched well.
Read my article for more info how to select canvas and how to prepare it for painting.

Also there is article by Landscapepainter, this is helpful as well if your stretcher bar is not adjustable or you dont have those wooden clips.

Also to note , that not all stretcher bars will be stretched. For example i have quite big 20 by 24 inch canvas with middle bar inside and no matter how hard I just tried it did not stretch enough. Next step is to use hand or magic cardboard. I use cheap canvas with thin stretcher where proper stretcher width would be 4 cm, i have only 2.5 cm ( 1 inch).

Another little trick you can put hand behind and push textile as you cover it with paint, however this is pain in the neck. But it is still doable.

I would suggest if it is still wet to use "hand" method and scratch with the knife all the excess in the sky and repaint it,Sand is not affected that much. It should be easy fix.

However if it does not work smudge all the painting to a nice neutral mud color let it dry and paint something with look out of the window or 2 seasons and use this disadvantage as your advantage.