- A pillar of rock that rises from the ocean, formed by surrounding softer ground eroding away.
- 1993, Dana Stabenow, Dead in the Water, →ISBN, page 53:
- Off the shore of still another island they found a stand of sea stacks, weird towers of rock sculpted by sand and wind and engulfed in flocks of gulls and cormorants, and as they banked for another look, Kate saw three bald eagles take wing.
- 2009, Claudia Nice, Down by the Sea with Brush and Pen, →ISBN:
- Some sea stacks are far off shore, while others like the one on the facing page, are in the tidal zone. Consider for a moment the contrasts the sea stack brings to the painting.
- 2011, Barry Lopez & Debra Gwartney, Home Ground: Language for an American Landscape, →ISBN, page 320:
- A tall island in the sea, a geologic bone, the sea stack represents rock harder than what once surrounded it and has been eroded away.