Ruth: Today we spent the day cycling up, into and around the caldera on Graciosa. It was a stiff, steady climb up the flank of the volcano before we popped through a tunnel in the crater wall and onto the floor of the caldera. 
The Azores, unlike many places, is becoming more wild rather than less. In the information centre there is an old picture of the caldera, when it looked like an open pit mine. It has now been lovingly replanted and transformed into a tropical paradise, with a maturing cryptomeria forest.
We descended into a cave at the bottom the crater through a long spiral staircase. (The Prince of Monaco had to rappel during his locally famous scientific expedition in 1889.) At the bottom of the cavern is a surprisingly large lake and some bubbling mud fumaroles. The cavern itself is the size of a football field and up to 50 metres high. 
After emerging from the cavern we explored the broader caldera including walking through a cave formed from a lava tube.

The best part of our ride was not inside the crater, but instead on the 5 kilometre circle road that runs around the outside of the volcano. We had panoramic views of the whole island, as well as the other four islands in the central group.