Where too next?

Hey r/learnmath.

I am a high school student, currently teaching myself second year calculus. I will be done quite soon, and after I plan to look into calc 3. However, I don't know what to do after that. I am an average smart kid (grades in the 90's etc. ) but I need a field of math that I can do something notable in to set myself apart when applying to universities. I find most areas of math fascinating, so if there is anything you guys could suggest I look into that might have opportunity for actual achievement, it would be greatly appreciated.