| Armathia | |
| Native Name: | Αρμάθια |
| Native Name Lang: | el |
| Nickname: | --> |
| Coordinates: | 35.4367°N 26.8636°W |
| Archipelago: | Dodecanese |
| Area M2: | or |
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| Coastline M: | --> |
| Country: | Greece |
| Country Area M2: | or |
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| Country1 Area M2: | or |
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Armathia (Greek, Modern (1453-);: Αρμάθια) is a Greek island belonging to the Dodecanese group in the eastern Aegean Sea. It is part of the municipality of Kasos. In the census of 1951, there were 8 recorded inhabitants, but it has since become uninhabited. At its peak, it sustained a community of over 100 who were mainly involved in mining the rich deposits of gypsum intended for export. It is now a tourist destination for day trippers from neighbouring developed islands. An observatory attracts wildlife observers.