Underground Lake Labyrinth

Underground Lake Labyrinth (地底湖の迷宮) is an unofficial name for the dungeon Sally finds in the 1st layer.

This dungeon was included in Episode 02 of the anime.

Plot
When Sally logs into NewWorld Online, she met up with Maple wasn't sure where to start. Because Maple needed fish scales to get a new shield, Sally decided to put off her own matters to spend time with Maple. To her surprise, fishing gave experience and she was on her way to progressing while spending time with her friend.

Because she knew how Maple ate the hydra, Sally decided to see if she could collect the scales by killing them while swimming. Before long, she not only collected enough scales to help Maple, she also discovered the labyrinth beneath the underground lake. Unlike normal dungeons, the entire dungeon is underwater so the progression was difficult. With Maple's friend messages as timers, Sally explored and eventually found the boss room.

Maple wished Sally luck before she logged out. Sally fought against the boss (giant fish, 巨大魚) underwater and defeated it before long. After defeating the boss, Sally learned Jack of All Trades and remarked that if she learned it before the boss fight, she would have lost.

Rewards
When Sally defeated the boss on her first solo attempt, she received the following UNIQUE SERIES: The manga insists the set came with boots. The web novel: ''Sally: "I know right〜! I didn’t get shoes so I bought black boots…with this, the uniform appearance is perfect!" (でしょー！靴は手に入らなかったから黒いブーツを買ったし…これで統一感は完璧！)''
 * Mirage (Shinkirō) : Confuses target‘s sense of vision so that it sees a mirage of the user in a different location. Effective against anyone other than user. Should an attack hit [Mirage] it will dissolve. Maximum usage is 10 times per day. Effect duration is 5 seconds.
 * Ocean (大海, alt. Oceania, Torrent) : Creates a shallow pool of water in a 10-meter radius within user. Contact with this water decreases AGI by 20%. Caster is unaffected by [Ocean]. Cannot be activated in mid-air. Maximum usage is 3 times per day. Effect duration is 10 seconds.