Yellow Lake
From billsfield.org
The Yellow Lake is a very large underground cave reached from the beach, it's main feature being a lake of spermaceti at its deepest point. Trunks of hardened spermaceti fall from the foggy ceiling into a network of rivers, which all flow into the lake.
Swarms of rod-shaped insects can be found patrolling the dark passages and hollowed caverns, which cause blindness if one gets too close.