From the back cover:
Evil Denizens of the Depths: The Sahuagin.
The sahuagin are known by many names. Some call them the Devil Men of the Deep; to others, they are simply the Sea Devils. This deadly race of aquatic beings has remained a mystery to surfacedwellers—until now. This fully illustrated 96-page accessory details the highly organized structure of sahuagin society, offers insight into the workings of the predatory sahuagin mind, and examines the worship of Sekolah, the dark sahuagin deity. The Sea Devils also includes a full description of a typical sahuagin village easily usable in any campaign setting, new spells that are granted to sahuagin priestesses, and a color poster detailing the sahuagin in all their variety.
This book is the second in a series of accessories that focuses on some of the most popular monsters in the AD&D® game. DMs and players alike should also look for Evil Tide, Night of the Shark, and Sea of Blood, a trilogy of Monstrous Arcana™ adventures centered around the Sahuagin.
User summary:
Also contains Rules for Underwater Adventures and a poster sized chart of the comparative sizes of Sahuagin and many other sea creatures.