I have nothing by way of hard details for you, but there is a gentleman called Harlan Hague who takes - and writes about - the most wonderful soft adventure tours that he has taken.

I remembered that he had been to the Galapagos (1999) and so found the link.

http://www.softadventure.net/peru.ecuador.article.htm

It was part of a much longer trip with visits to Machu Piccu etc but there is a section on the 5 day cruise he did through the islands. There are some reference details at the end of the article in case they may be of some help. I have contacted the author a couple of times before about other trips he has taken and he was most helpful.

It looks wonderful! :) Megan Brisbane, Australia