HAL Shore Excursions
I used the ship's shore excursion; the cost, since transportation from the port to Lima must be arranged and the tours available in town would cover more sights than I had time for. An internet search will, however, reveal quite a few vendors for both of these locations.
Another Tour Source
We didn't use this service, but I met several people on our cruise who did and they were pleased with their experiences. The Mirabus, which is among several options on this site was mentioned especially, but every tour is not always available every day; plan to research it in advance. LIMAEASY