As you pointed out, the horizon is titled. this can be fixed easily by rotating the picture and cropping. Which software do you use for edits ?
You have some great subjects in the picture, but you didn't capture them well. they occupy lesser area in frame and the viewer is distracted to ther other elements in the picture.
What to do: in this particular picture, you could have gone closer, taken a shot from lower angle to capture the guys with sky as background, you will be able to fill the frame with the boys and have a colorful background...
I like this as a photograph. The cluster of figures is interesting. I think I would have toned down the brightness of the sunset over the mountains and on the water.
you should have cropped the blurry part on the right side and rotate the picture a bit so that the horizon would be perpendicular. Otherwise, it's a good picture with nice colors.