The Inland Sea, sometimes called Il-Qawra in Maltese and also known as Dwejra, is a lagoon of seawater on the island of Gozo linked to the Mediterranean Sea through an opening formed by a narrow natural arch.
It was probably formed where a geological fault in the limestone had created a sea cave and the roof then collapsed.
On one side there is a gently shelving stony beach with several fishermen's huts.
On calm days fishing boats, known in Maltese as luzzijiet, can pass through the tunnel. Some of the boats are used to take visitors through the archway and then for a tour of the nearby cliffs and other sites, mainly to the Fungus Rock and to the site of the former large natural arch in the cliffs called the Azure Window.