>What is known about isometric actions on $\mathbb S^n$ such that the quotient space is homeomorphic to $\mathbb S^n$? **Comments.** - I am mostly interested in (maybe trivial) properties of such actions for large $n$. Say, is it true that any such action is generated by rotations around $\mathbb S^{n-2}$'s? - I see that the orientation preserving part of Coxeter's group has this property. - Now I see that there are other examples for $\mathbb S^3$, thanks to Lee Mosher. It seems that taking joints you get such examples in higher dimensions