The Quill is a stratovolcano located in the south of the island of St. Eustatius in the Caribbean Netherlands. Volcanoes in this region are formed as a consequence of the subduction of the North and South American plate beneath the Caribbean plate.

The 800 m wide and 300 m deep summit crater of the Quill is completely overgrown with a tropical, pocket-sized rainforest. The cone of the volcano is built from pyroclastic deposits, reflecting its explosive history.

The age of the most recent eruption remains debated mainly because of the paucity of charcoal suitable for dating.

The last eruption probably occurred around 1700 ± 90 year B.P., circa 250 CE. The volcano does not show signs of current unrest but geologically speaking the volcano is "active".

KNMI measures several geophysical parameters to monitor the state of the volcano.