Overview

Be careful! Once you leave, you cannot re-enter this instance.

Go to the Special Vending Machine. /navi malangdo 218/165 Buy an Octopus Hunting Spear there. You need Silvervine Fruits for them.
Open the box and keep that item with you whenever you enter the instance.

Starfish and Weird Entrance.

Talk to the Instance Manager to generate and enter the instance.
You'll be warped into a cave with 4 warp portals. Enter one of the portal and walk until the end of the tunnel. There is no need to kill everything and the order of the portals don't matter.
Kill the Octopus Leg.
After killing 4 Legs, you'll be teleported back. Prepare for the boss fight.
Crossing the new warp in the north you'll reach the boss room. There will be the Giant Octopus, several Octopus Legs and Octopuses. Kill the MVP.

Enemies

Name	Level	HP	Size / Race / Element
Hydra	34	854	Small / Plant / Water 2
Stapo	95	8,805	Small / Formless / Earth 2
Octopus Henchman	90	854	Small / Fish / Water 2
Mercenary Squid	95	120,000	Small / Fish / Water 2
Octopus Leg	90	500,000	Small / Fish / Water 2
Giant Octopus	95	500,000	Large / Fish / Water 2

Card	Type	Description
Hydra Card	Weapon	Increases physical damage against [Demi-Human] race targets by 20%.
Stapo Card	Accessory	Enables the use of [Find Stone] Lv 1 and [Stone Fling] Lv 1.
Gigant Octopus Card	Armor	Enables the use of [Water Ball] Lv 5.