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This quest has a quick guide found here.
It briefly summarises the steps needed to complete the quest.

Horror from the Deep is an experienced quest revolving around the mysterious disappearance of Jossik, keeper of the Lighthouse near the Fremennik Province. As the title suggests, the investigations lead to the discovery of very dangerous creatures living beneath the lighthouse.


Start point Speak with Larrissa, who is outside the Lighthouse, north of Barbarian Outpost. Speak with Larrissa, who is outside the Lighthouse, north of Barbarian Outpost.
Official difficulty Experienced
Description The lighthouse protecting Kandarin's northwestern 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.

Length Short


Items required


Enemies to defeat


Getting started

Items required: 60 steel nails, a hammer, 2 planks, swamp tar, a tinderbox, molten glass, 1 of each elemental rune, 1 arrow, and 1 sword.

Start by speaking to Larrissa outside of the lighthouse (north of Barbarian Outpost). A fairy ring is right next to the lighthouse (fairy ring code ALP).

NOTE: Bring food due to the basalt platform having a high failure rate with low level agility.

Fixing the lighthouse

The lit lighting mechanism

  1. After speaking to Larrissa, go down south of her jumping across the basalt platforms and into the Barbarian Outpost.
  2. Talk to Gunnjorn (in the Barbarian Outpost Agility arena) and get the lighthouse key; you can get your two planks here, which respawn north-east of Barbarian's Outpost.
  3. Use both planks on the broken bridge east of Larrissa. You will need to use a plank (not oak planks!)and 60 steel nails (for both the west side and the east side of the broken bridge). Note that you can cross the bridge before completely fixing it. Also, the bridge will not look any different after fixing it. This is normal. Check your quest log to make sure it says that you've fixed the bridge.
  4. Go and talk to Larrissa again.
  5. Go up to the 1st floor[?]. Search the bookcase and take all the books; flip through the lighthouse manual and the ancient diary.
  6. Go up one more floor, and use the following items on lighting mechanism in this order: swamp tar, tinderbox, and molten glass.

The door

The strange door.

Go down the iron ladder into the basement to find the door.

  1. Use all of your basic elemental runes on the door (fire, water, earth, and air). If you have more than one rune i.e. 500 air runes it will only use one air rune. So don't worry you will not use all 500.
  2. Use your sword (any type, but you will not get it back), and your arrow (any type, but you will not get it back. Bolts will not work).
  3. If you need to bank, use your Games necklace/Minigame Group Finder to go back to Barbarian Assault, or use the fairy ring back to Zanaris to bank.
  4. Get good armour (Rune), or Magic armour (Mystic); bring many mind, chaos, death, or blood runes and enough runes to cast several of each elemental spell (wind, water, earth, and fire); get a good weapon for Melee, and some Ranged equipment.

The fight

  1. Go through the eastern part of the door and down the ladder.
  2. Talk to Jossik, be prepared to fight two Dagannoth.
  3. The first one is easy if you have Protect from Melee. If you don't have Protect from Melee and your Combat level is relatively low, it might be wise to safespot behind the rocks in the room. It can be killed by all forms of combat.
  4. Then, right after you defeat it, there will be a cut-scene, and you will fight a harder monster.
  5. You have to attack the Dagannoth mother by colour if you want to deal any damage.

A safespot for fighting the Dagannoth mother. Protect from Ranged should be active at all times during the fight.

  • Green means use ranged attacks.

If you cannot see the colour changes very well, look at the chat box. Using the wrong attack does no damage to it. Also, you can safespot her by using the stalagmites in the room. If you do it right, you can get the mother stuck behind a stalagmite where you can stand behind and not lose any health points.

The best way to defeat her is to ignore the ranged and melee forms, since she has too high Defence against those attack types for them to be worthwhile. Use an air staff and switch spell types in the correct order.

The Mother can be safespotted by melee, and if you have a good enough weapon (e.g. dragon weapons), you can completely avoid all Ranged and Magic; you don't need food or decent armour, and you can wait until the orange stage repeatedly.

Protect from Missiles can be flicked as you safespot her, which will cause her to do no attacks at all. Bolt and Blast spells will tear through her, requiring no food at all.

She can detect Prayer, and will automatically use the opposite attack type when you use prayer. By default, she ranges at a distance and melees up close. Her melee attacks are stronger.

Note: If there are any dropped items at the time the Dagannoth Mother's death, you will not be able to get them back. You are still able to loot your items if you died within the boss room, but only before the Dagannoth Mother is killed.

After the fight

You'll get a Rusty casket after you defeat the Dagannoth Mother. Go to the 1st floor[?] 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.)

Congratulations! Quest complete!


Horror from the Deep reward scroll.png


  • Unlike most quests, the reward screen for Horror from the Deep says 'You have survived the Horror from the Deep!' rather than 'You have completed Horror from the Deep!'
  • While in instanced versions of the lighthouse, you no longer see the fairy ring outside which was added later.