Gyali (or Yiali) is a small, uninhabited volcanic island located near Kos and Nisyros in the Dodecanese group of Greece. It is known for its unique geological features, primarily consisting of pumice and obsidian, which have been formed by past volcanic activity. The island is divided into two parts by a narrow isthmus: one side features hills of white pumice stone, while the other contains deposits of obsidian and perlite, making it a distinctive natural environment.

Gyali is mostly uninhabited and used for mining purposes, as the pumice and perlite are extracted and exported. Its landscape, characterized by bright white beaches and crystalline waters, makes it a beautiful spot, although it remains largely undeveloped. The island is accessible by boat, and visitors often take day trips from nearby islands like Kos or Nisyros to enjoy its pristine beaches and explore the volcanic terrain.

While not a tourist-heavy destination, Gyali’s stark natural beauty and geological significance make it an interesting site for those interested in volcanology or looking for a quiet beach escape.