The crater Furna do Insofar is in the South-Eastern part of the island of Graciosa. The island of Graciosa, the northernmost island of the Central group of the Azores Islands, and is one of nine inhabited Islands of the Azores archipelago. Due to the fact that the island has an undulating landscape of low hills and small volcanic caves, the island of Graciosa is often called "elegant". It is worth noting that the island was declared a biosphere reserve by UNESCO.

The crater Furna do Insofar is a large lava cave and makes a striking impression. The arch of the crater is shaped like a dome. The crater Furna do Insofar also called "Sulphur grotto" due to the fact that there is a lot of sulphur and thermal springs. In addition, there is a lake inside with cold sulphur water. The diameter of the lake is 130 meters and the depth is 15 meters.

The crater Furna do Inshore and crater Furna da Maria Encantada are part of a geological formation Caldeira da Graciosa, which is a distinctive feature of the landscape of the island. The length of the crater Furna do Insofar is 197 meters and a height of 80 meters and a width of 172 metres. The path inside the crater Furna do Insofar is through the tower, whose height is 37 meters after you will need to go down the spiral staircase, which has 183 steps.

In the nineteenth century, the cave was thoroughly researched. In "Sulphur grotto was visited by many famous people. The grotto was investigated by the famous naturalist Ferdinand andré fouqué and Georg Hartung.