Located at the crossroads of the Equatorial Counter current and the colder Humbolt Current, the waters surrounding the island are rich with nutrients that attract whales, sharks, dolphins, sea lions and numerous other big animals. No landing is permitted on the islands of Wolf and Darwin but it is around these more remote islands that some of the most impressive encounters occur. Land tours are a big part of any Galapagos itinerary as well as visits to several visitors centers and research stations.