The Spanish Antarctic Base on Deception Island is called "Gabriel De Castilla". It was originally opened in 1988 as a refuge (with a single building) but it was upgraded to full base status during the 1998/99 Austral season. It is situated at the foot of an active volcano with volcanism being one of the main studies.

It has accommodation for 16 persons and is administered by the Spanish military as opposed to the other Spanish Base (Juan Carlos 1) which has a civilian administration.

Note: This cover has the special Deception Island Base postmark as well as two different base cachets and the Spanish support vessel "Hesperides" expedition cachet.