Undersea Tunnel B4 iz_dun03 Dungeon Midgard Byalan IslandWorld map: Lv 11~50Monsters Lv 14–53 N 300 × 300 cells · Warp portals: 2 On the world map: Undersea Tunnel F4 (Midgard) Map rules No memo Monsters 6 Hydra Lv 14×40⟳ 5 s – 7 min 53 s Phen Lv 26×45 Marine Sphere Lv 28×20 Swordfish Lv 30×40 Marc Lv 36×40 Merman Lv 53×3⟳ 30 min – 50 min Exits 2 Undersea Tunnel B3iz_dun02 Dungeon Undersea Tunnel B5iz_dun04 Dungeon