Note: Reaching Skellige requires the completion of main quest "Destination: Skellige."
In the Heart of the Woods
Prerequisite: None | Suggested Level: 22
You can start this side quest from the Kaer Trolde Harbor Notice Board, but you'll have to visit Fayrlund to get more information. There's a group of villagers gathered on the town's edge; talk to them to learn that some woodland spirit has killed on of the residents here.
Step one is to take a look at the woods nearby. Use your Witcher Senses in the three search areas to find claw marks and additional bodies. You're dealing with a leshen here, so read your bestiary to learn more - bombs, oils, and Igni will help with the upcoming battle.
Head back to town to speak with Harald and Sven. The former wants you to honor the spirit, while the latter wants it dead. If you choose Harald's way, you'll have to place a wolf's heart at the beat's alter to sate it. There's a pack near the altar, so you can easily loot one. Return to Harald after making your offering to be confronted by Sven and his boys. Deal with this as you'd like to complete the quest.
If you choose Sven's way, you'll first have to use your Witcher Senses to find out which villager has been marked by the beast. Once you do, return to Sven and decide what to do with her. Step two is to head back into the woods and destroy the leshen's three totems. Then you can head to your maker and face the beast. Defeat it and its band of wolves, and return to Sven for your reward.
The Family Blade
Prerequisite: None | Suggested Level: 15
This quest also comes from the Kaer Trolde Harbor Notice Board. Check it out to learn that Jarl Crach an Craie is offering a reward for the return of his family's sword. Head east to your marker to find a camp of renegades. Take them out, loot the bodies, and read the journal you find to discover that the blade is a band-occupied fort on the southern side of the island.
Head to this new marker to find more renegades around a harpy's nest. Kill them all, then search the bodies for another journal; this one will tell you the blade is with a third set of thieves at the Whale Graveyard on the northeastern edge of the island. Head there, take them out, and loot the bodies to find the all-important blade. Return this to the guardsman at Kaer Trolde to complete the quest.
Gwent: Skellige Style
Prerequisite: None, but requires "Practicum in Advanced Alchemy" to complete. | Suggested Level: N/A
Check the Kaer Trolde Harbor Notice Board to learn of some Gwent players in Skellige. The first is the druid Ermion. Track him down and beat him to learn of two more good players. The first is Crach, and beating him will unlock another match against a tailor named Sjusta. The second is Gremist, but in order to duel him, you'll need to complete "Practicum in Advanced Alchemy." Beating him unlocks a match against Madman Lugos. You'll need to trump all four players to complete the quest.
Practicum in Advanced Alchemy
Prerequisite: None | Suggested Level: 24
West of the Whale Graveyard marker is a place called Gedyenith Grove, where you'll find several druids. When you find it, one of them will be arguing with an aged alchemist named Gremist. Speak to him to learn that Gremist refuses to take an apprentice. Pay him a visit, and he'll agree to teach you advanced techniques if you do three favors for him.
The first is to collect a pimpernel from the woods to the south. Use your Witcher Senses in the area to find a special object… which isn’t the plant you need. Another druid will show up and say one of his fellows has gone missing. Use your Senses again to find a set of tracks; follow these to find the missing druid flirting with a succubus. Cut her down, then follow the scent trail to her lair. You'll find a pimpernel in the back of the cave.
The second favor is to get Skellige spirit from an abandoned distillery. The marker is nearby the succubus' lair, so head up the mountain to find the place. You'll have to battle a cyclops inside, but then you'll be free to explore. Check the buildings to find the distiller's recipe. Now use your Witcher Senses to find mash (it's up the ladder near the machinery). Add this to the cauldron, then ignite the kindling below with Igni. Extinguish it after a moment, then pull the nearby lever to distill the spirits. Pick this up and be on your way.
The third favor is to find the druid Fritjof and bring him back to Gremist. You'll find him in the town of Blandare in the center of the isle. He'll agree to see Gremist if you help him with a ritual of his own. Follow him to his altar, and a few waves of foglets will attack. Fend them off to make Fritjof happy, and he'll head off to see his pal.
Return to Gremist, and he'll tell you that you cannot be present for the ritual. Return the next day to find him and Fritjof rather drunk. Join them to complete the quest.
Fists of Fury: Skellige
Prerequisite: None | Suggested Level: 30
Read the Kaer Trolde Harbor Notice Board to learn about a fighting ring across the islands. There are three brutes to face: Valgard in Kaer Trolde, Grim in Arinbjorn, and Einar in Harviken. Defeat all three to unlock a final bout against Olaf at the arena near Urialla Harbor. Take down this bear (yes, you must fistfight a bear) to become Champion of the Isles.