Cataract Caverns

From publisher blurb: The churning, freezing waters of the subterranean river surge through the arched inlet and into Cataract Caverns, so-named in honour of the resident whirlpool Cataract, a thirsty sink-hole into the depths of the earth. A wealthy artisan has lost something precious to the river and believes the prize may have fallen victim to Cataract. Able hands and brave spelunkers are needed to explore the caves and retrieve the object.