On March 17 my wife and I did the Ribeiro Frio slot canyon in Madeira. We went guided (Discovery Island) since we didn't want to haul all of our gear overseas just for one day of canyoneering. The water was very cold in the canyon, but it was a really good one complete with some real slot sections. We chose Ribeiro Frio because we were told it was the best slot on the island. Here are some photographs. I'll post some more later.