Shiretoko means "the end of the earth" in Ainu. Shiretoko was recently added to the list of UNESCO list of world natural heritage sites. link to shiretoko, full list. Shiretoko is a very special place. There are very few visitors to the interior of the park, which is where i suggest to go directly and avoid the bus loads of sightseers. I recommend the 2-3 day traverse.

Public transportation: take the JR Kushiro line from Kushiro or Abashiri to Shari (shiretoko shari). Just in front of the train station is a bus to the park.