I've already been to 3 of the Azores islands and I cant wait to visit the other 6. On Graciosa island, one of the attractions is the Sulphur Cave, a large cave of volcanic origin.
The 1st card was sent by Manú (I think) and the other one was sent by Lurdes.
This place is one of the portuguese sites on the UNESCO Tentative List.
Photo by Jorge Góis
Sulphur cave is located in the only caldera of the island, whose origin is related to the collapse phase and drainage of a lava lake in the interior of the caldera. It is formed by an unique and huge dome that shows the existence of basaltic prisms. its maximum altitude is 100m and its diameter is 150m. In the bottom of the cave a big lagoon can be seen. There is a permanent fumarolic activity which exhales the CO², H²S, H² gases There are two holes in this cave that allow the entrance of the sun light. - in: http://whc.unesco.org/en/tentativelists/566/
Foto: Karl-Heinz Raach
The access to the cave is made through a tower with about 37 meter high and a stairway with 183 steps.