Belly of the Black Whale is a Pathfinder adventure for four 15th-level characters. This adventure continues the Agents of Edgewatch Adventure Path, a six-part monthly campaign in which players take on the role of city watchdogs and dole out justice to Absalom's most nefarious criminal elements. This volume also includes new rules and exciting lore regarding Absalom's notorious prisons, the slithering snake goddess Ravithra, and a throng of new monsters and villains for urban fantasy campaigns.

Each monthly full-color softcover Pathfinder Adventure Path volume contains an in-depth adventure scenario, stats for several new monsters, and support articles meant to give Game Masters additional material to expand their campaign. Pathfinder Adventure Path volumes use the Open Game License and work with both the Pathfinder RPG and the world's oldest fantasy RPG.