Terceira island covers an area of 401.9 square kilometres, with 30.1 km in length and 14 km at its maximum width. The highest point of the island is at 1'021 m in the Serra de Santa Bárbara.
Portugal 2017, Algar do Carvão.
The stamp was issued in the series "Geoparque Azores".
Algar do Carvão is a 90 metre-deep volcanic chimney formed approximately 3'200 years ago after the magma drained from the main chimney receding to the magma chamber.