Carrapatelo Dam

This was the first dam to be built on the Douro River and at 35m high is one of the biggest single chamber locks in the world.

It was a weird feeling watching the water gushing in to this confined space. It took only 20 minutes to get to river level but all the chairs and railings (and people!) had to be removed from the middle part of the deck because of a concrete bridge overhead. Now that could be nasty.