Cruising on the Yenisey

Several years ago I was fascinated by a traveller's account of a trip on the Yenisey River of eastern Siberia. This river runs from southern Siberia all the way to the Arctic Ocean, and along its upper reaches it is the main transportation artery for many remote towns. I never was able to find any information on how to travel on this river, but have now discovered a way, thanks to the Lonely Planet Russia guidebook.
Sib Tour Guide (http://sibtourguide.com/) is a Website run by a resident of Krasnoyarsk who offers booking for Yenisey River cruises, as well as a homestay with the site owner and his family, and an apartment for rent in Krasnoyarsk, a town on the TransSiberian Railway. Nature lovers can also stay at a typical Russian dacha in the area.
The cruises can last for several days, and the pictures of the ships are appealing. Some cruises run all the way to Norilsk, a major mining centre near the Arctic Ocean. However, Norilsk is closed to most foreigners expect by special invitation. Not a bad thing, perhaps, since it is also one of the most polluted cities in the world.
The chance to see such a remote part of the world in relative comfort sounds very intriguing, at least to me. Cruises run only in summer.