A NOTE ON HYPERBOLIC 3-MANIFOLDS OF THE SAME VOLUME

We describe a method for constructing an arbitrary number of closed hyperbolic 3-manifolds of the same volume. In fact we prove that many hyperbolic 3-manifolds of finite volume have an arbitrary number of non-homeomorphic finite covering spaces of the same degree and hence the same volume. This applies, for example, to all hyperbolic 3-manifolds whose universal covering group is a subgroup of finite index in a Coxeter group generated by the reflections in the faces of a hyperbolic Coxeter polyhedron. It also applies to all hyperbolic 3-manifolds of finite volume with at least one cusp.