The Blue Grotto and St. Francis’s Grotto form a complex consisting of two caves interconnected by an underground passage, with two openings to the sea and one from the land. The formation of this complex, similar to all coastal caves on the island, is the result of water mixed with carbon dioxide seeping in. Over time, in addition to creating stalactites and stalagmites, this corrosive process widened cracks in the rocks, causing instability and the subsequent collapse of the rock itself, leading to the formation of the caves.
\nNumerous fossil remains have been found inside the caves, bearing witness to the sea level changes that occurred over millennia. Looking from the coast, only the entrance to the Blue Grotto is visible, while that of St. Francis’s Grotto remains hidden by the cliff, located about twenty meters further to the left.<\/p>\n","protected":false},"featured_media":144,"parent":0,"template":"","location_type":[89,99],"target_type":[114,115,116],"class_list":["post-885","location","type-location","status-publish","has-post-thumbnail","hentry","location_type-natural-beauty","location_type-nature-reserve","target_type-adults","target_type-children-and-teenagers","target_type-families"],"acf":{"address":"Contrada Oliastrello, 90051 Ustica, Sicily, Italy","gallery_image":[{"ID":146,"id":146,"title":"IMG_3738","filename":"IMG_3738.jpg","filesize":215032,"url":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738.jpg","link":"https:\/\/usticaexperience.com\/en\/point-of-interest\/the-blue-grotto\/img_3738-2\/","alt":"","author":"1","description":"","caption":"","name":"img_3738-2","status":"inherit","uploaded_to":885,"date":"2025-05-12 14:27:58","modified":"2025-06-11 16:40:00","menu_order":0,"mime_type":"image\/jpeg","type":"image","subtype":"jpeg","icon":"https:\/\/usticaexperience.com\/wp-includes\/images\/media\/default.png","width":1536,"height":1152,"sizes":{"thumbnail":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738-150x150.jpg","thumbnail-width":150,"thumbnail-height":150,"medium":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738-300x225.jpg","medium-width":300,"medium-height":225,"medium_large":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738-768x576.jpg","medium_large-width":768,"medium_large-height":576,"large":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738-1024x768.jpg","large-width":1024,"large-height":768,"1536x1536":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738.jpg","1536x1536-width":1536,"1536x1536-height":1152,"2048x2048":"https:\/\/usticaexperience.com\/wp-content\/uploads\/2025\/05\/IMG_3738.jpg","2048x2048-width":1536,"2048x2048-height":1152}}],"additional_information":"","related_locations":false,"short_description":"Grotta Azzurra Ustica evokes emotions every time you enter it; the atmosphere instantly becomes magical, shifting between light and shadow.","opening_hours":{"description":"
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