Great Lake

Great Lake (ひょうたん湖) is a large lake that lies in the northern part of the Great Forest of Tob and extends to the southern end of the Azerlisia Mountains.

Background
This enormous lake has a width of approximately twenty kilometers, and was shaped like an inverted calabash or ladle. Its waters flow between the southern tip of the Azerlisia Mountains and Great Forest of Tob.

The Lizard Man Heroes Arc
The Great Lake is the main setting for this arc, specifically the Wetlands, where the lizardmen reside. The Great Tomb of Nazarick plan to expand its power and turns its attentions to the demi-human tribes of the Great Lake. Wishing to convert the strong bodies of the lizardmen into powerful undead, Ainz sends Cocytus to carry out the campaign.

After arriving at the southern part of Great Lake, Cocytus sends out a messenger to deliver the message to the lizardmen tribes. Instead of cowering in fear of the threat, it promotes the lizardmen tribes to unite and overcome the invasion. Led by Green Claw, the tribes unite under one banner and face the undead army. After eight days of preparing for battle the lizardmen successfully become one tribe, they manage to obliterate the first wave of the attack and later fend off the second.

Cocytus seeing that he is on the verge of defeat immediately sends out Iguva=41. The lich, though powerful, also falls to the combined might of the tribal chiefs. As the last undead falls it leaves the lizardmen in triumph.

The united tribes' victory do not last for long as an even stronger and better equipped undead army is assembled right outside the Green Claw's village. The lizardmen witness the fantastical creatures from Nazaraick and tremble at their power. An ultimatum is given by Ainz Ooal Gown, who was impressed by their ability to overcome his previous army. Rather than destroying them, Ainz offers to give them a chance. If they are able to defeat his warrior, Coyctus, he promises to forever abandon his attempts to conquer the lizardmen.

The tribal chieftains seeing no other alternative agree.

Layout
The lake is divided into two parts. The upper lake and the lower lake. The upper lake is relatively deep, hence large creatures tend to gather there while the lower lake is inhabited by smaller creatures.

Wetlands
Located at the southern end of the lower lake is a large region where the lake and the wetlands blended into each other. Several tribes of lizardmen live here and their villages are located over the muddy lands.

Lizardmen
The Lizardmen dwell in the southern part of the the Great Lake.

Toadmen
The Toadman inhabit the northeastern side of the Great Lake.

Trivia

 * Supposedly, the Great Lake was once frozen over in the past.
 * The lizardmen are just one of the recent tribes to establish a home near the Great Lake.