Gleason's Gielinor Guide

This quest has an in-depth guide.

It contains a more detailed description of dialogue, cutscenes, and storyline.

Details

Start point	Talk to Larrissa outside the Lighthouse north of Barbarian Outpost. Show on map
Official difficulty	Intermediate
Official length	Short
Description	The lighthouse protecting Kandarin's north-western coastline has mysteriously stopped operating, and contact with the lighthouse keeper Jossik has been lost. The Council would greatly appreciate it if somebody could discover for them what has happened to this most vital landscape feature.
Requirements	35 Agility ^[boostable] ^{[not required to start]} Completion of Alfred Grimhand's Barcrawl ^{[required to start]}
Items required	Fire rune Air rune Water rune Earth rune Any sword or longsword that you are willing to lose (except rusty sword and prop sword) Any arrow (except ogre arrows and training arrows) Molten glass Tinderbox Hammer 60 steel nails 2 regular planks (can be obtained from Barbarian Outpost) Swamp tar At least one combat style to defeat the Dagannoth Mother - she cycles every 18 seconds between only being vulnerable to one of six different types of attack Highly recommended to bring means to deal damage with all of the elemental Magic types (air, water, earth, and fire spells) You may also bring means to deal Ranged and Melee damage (she has high resistance to melee)
Recommended	40 Prayer for Protect from Missiles against the Dagannoth Mother's ranged attacks 50 Combat level Armour and some food 13 Magic+ to cast each elemental spell Fast travel to several locations Lighthouse to start the quest plus one additional trip - fairy ring ALP, games necklace to Barbarian Outpost or Minigame Teleport to Barbarian Assault Barbarian Outpost (1 trip) - games necklace or Minigame Teleport to Barbarian Assault
Enemies to defeat	Dagannoth (Horror from the Deep) (level 100) (can be completely safespotted) Dagannoth Mother (level 100) (with use of a safespot and Protect from Missiles, all damage can be negated)

Walkthrough

To begin the quest use the fairy ring code ALP to teleport to the lighthouse. Alternatively, one could teleport to the Barbarian Outpost using a games necklace or Grouping teleport then hop over the rocks to the north to reach the lighthouse.
Talk to Larrissa. ( 1•1•1•3)…
1 With what?
1 But how can I help?
1 Okay, I'll help!
3 I'll see what I can do
Run east to the second bridge, use a plank on it.
Jump the bridge and use a second plank on it.
Head over to Barbarian Outpost, enter the Barbarian Outpost Agility arena and talk to Gunnjorn for a key. In order to enter the arena, you need to have completed the barcrawl miniquest.
- While at the outpost, prepare for the battle against the Dagannoth and Dagannoth Mother.
- (Optional) Complete a lap of the Agility course to complete a medium Kandarin task.
Talk to Larrissa again.
Go to the roof of the lighthouse and use the swamp tar, tinderbox, and molten glass on the lighting mechanism.
Climb down to the basement, use 1 of each elemental rune, any sword, and any arrow on the strange wall.
Open the eastern strange wall of the doorway, climb down the ladder and talk to Jossik.
Kill the level 100 Dagannoth then the level 100 Dagannoth Mother by using any elemental magic attack from the table below.

Colour	Weakness	Attack Using
White	Air spells	Wind Strike, Bolt, Blast, Wave, or Surge.
Blue	Water spells	Water Strike, Bolt, Blast, Wave, or Surge.
Brown	Earth spells	Earth Strike, Bolt, Blast, Wave, or Surge.
Red	Fire spells	Fire Strike, Bolt, Blast, Wave, or Surge.
Orange	Melee	Melee attacks.
Green	Ranged	Ranged attacks.

Congratulations, quest complete!
Take the rusty casket you received from killing the Dagannoth mother to Jossik upstairs to receive a damaged prayer book (choose any, you can buy the others from him afterwards for 5000 coins each). If you didn't receive a casket, he will give you one during the conversation.

Rewards

2 Quest points
4,662.5 Magic experience
4,662.5 Strength experience
4,662.5 Ranged experience
A damaged book of your choice which, when complete, will become: a Holy book (Saradomin), an Unholy book (Zamorak), or a Book of Balance (Guthix).
- Further damaged books can be purchased from Jossik for 5,000 coins each, even if you have not filled your other book(s).
Access to the Lighthouse general store and the Dagannoth caves underneath.

Unlocks:

Dagannoth mother accessible in the Nightmare Zone.

Horror from the Deep/Quick guide

Details

Walkthrough

Rewards

Sources & credits

1	With what?
1	But how can I help?
1	Okay, I'll help!
3	I'll see what I can do