From YPPedia

Here is a list of all of the Archipelagos or exact Islands on the Sage Ocean which have been threatened by a flotilla.

1. Admiral Island (May 25, diabled then reactivated on May 29)
2. Caravanserai Island (June 1)
3. Ventress Island
4. Mass Flotillas: Gull Archipelago, Osprey Archipelago, and Ibis Archipelago or Pelican Archipelago. (June 4)
5. Mass Flotillas: Basset Island, Osprey Archipelago, Ibis Archipelago and Pelican Archipelago. (June 8)

See Also

• Official game documentation for Flotillas
• Ice forum discussion thread
• Flotilla Hunters of Sage