Horror from the Deep/Quick guide

This quest has an [[{{#replace:Horror from the Deep/Quick guide|/Quick guide}}|in-depth guide]].

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

Details

Start point	Speak with Larrissa, who is outside the Lighthouse, north of Barbarian Outpost. <maplink group="pins" align="center" text="<b>Show on map</b>" plane="0" y="3636" x="2508" zoom="2" mapID="-1"> {"features":[{"type":"Feature","geometry":{"coordinates":[2508.5,3634.5],"type":"Point"},"properties":{"mapID":"-1","providerID":0,"description":" X/Y: 2508,3634 ","group":"pins","icon":"greenPin","plane":0,"title":"Start point"}}],"type":"FeatureCollection"} </maplink>
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
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 Means to deal melee and ranged damage Means to deal damage with air, water, earth and fire spells
Recommended	40 Prayer for Protect from Missiles against the Dagannoth Mother's ranged attacks 50 Combat level Armour and some food Level 13+ Magic, in order to cast required spells to defeat the creature. Fast travel to the Lighthouse (Fairy Rings to ALP or walk from the Barbarian Outpost using a Games Necklace or grouping teleport to the Barbarian Assault)
Enemies to defeat	Dagannoth (level 100) (can be completely safespotted) Dagannoth Mother (level 100) (can no longer be 100% safespotted - ensure you can protect yourself from ranged attacks if nothing else)
League notes	Unlocking Fremennik✓ will auto-complete the quest Fremennik✓ required to complete this quest

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!

After the fight

You'll get a rusty casket after you defeat the Dagannoth Mother.
- Go to the 2nd floor[US] of the lighthouse and show it to Jossik to finish the quest. (Note: If your inventory is full when killing the Dagannoth Mother you will not receive the casket. Instead, go and talk to Jossik upstairs who will say he picked up the casket after you left it on the ground.)

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.