What the achievement asks
Defeat all sixteen rare creatures found on the Siren Isle. Fifteen points, account-wide.
Unlike the Adventurer achievements in the other zones, this one is not a menu. It wants every one of the sixteen, so a rare you skip is a rare you will come back for.
Where they are
| Rare | Coordinates |
|---|---|
| Nerathor | 26.8 65.4 |
| Gravesludge | 58.4 68.6 |
| Stalagnarok | 39.6 56.2 |
| Bloodbrine | 32.8 71.6 |
| Shardsong | see below |
| Ghostmaker | 54.0 32.4 |
| Grimgull | 34.0 30.8 |
| Gunnlod the Sea-Drinker | see below |
| Snacker | 71.6 23.6 |
| Wreckwater | 46.8 78.0 |
| Coralweaver Calliso | 61.8 89.4 |
| Siris the Sea Scorpion | 55.6 82.6 |
| Chef Chum Platter | 65.8 85.0 |
| Plank-Master Bluebelly | 60.2 88.6 |
| Ikir the Flotsurge | 32.8 73.6 |
| Asbjorn the Bloodsoaked | 63.6 86.8 |
Two without a published spot
Shardsong and Gunnlod the Sea-Drinker have no fixed coordinate in Wowhead's zone data. Both are found on the island rather than at a point, so a rare-scanning addon or a group is worth more for those two than any coordinate would be.
The Seafury Tempest changes what is up
The island runs a storm phase, and which rares are available shifts with it. If several names on your list are stubbornly absent, switching phase is more productive than another lap.
Suzie Boltwrench at 69.13 49.10 moves you between the ordinary island and the storm.
Do it with the rest of the isle
The Siren Isle is small and everything on it overlaps. The caches of Treasures of the Storm, the gems of A Choir of Citrines and the weeklies of Siren-ity Now! all happen on the same few laps, and since this achievement needs all sixteen rares, you will be making those laps anyway.
Where it fits
One of the pieces of You Xal Not Pass, which rewards the Shadow of Doubt mount and is part of Worldsoul-Searching, the War Within meta.