After summitting on Pico de Orizaba we used public transport to reach Jalcomulco - an up and coming centre for river-rafting trips, though still relatively undiscovered by non-Mexicans. Ironically, the Rio Pescados takes meltwater from Orizaba peak, so in a way we felt we were still on the mountain! We used this company to make a 3 night stay, which we'd thoroughly recommend: www.raftingsinlimite.com