Instances

Squad/Solo Locations
Squad instances are 1-3 player missions.

Satria

 * Dankit Island
 * Factory 501
 * Okki Island
 * Alakur Island

Panthean Plateau

 * Facility 902
 * Kyris
 * Fort Krigg
 * Ignum Monastery
 * Nerion's Castle

Linos

 * Port Naori
 * Ardos Monastery
 * Avesten Tower
 * Thais Temple

Artemian Mountains

 * Thandi Drilling Station
 * Tau Experimental Platform
 * Palon Prototype Plant
 * Kyros Caves
 * Cronnel Platforms

Glyceria

 * Port Usuni
 * Icy Winds Canyon
 * Donholk Glacier
 * Thorneus's Camp

Tisiphone

 * Saiban Archipelago
 * Syblian Heights
 * Thetin Rift
 * Lanber Catacombs

Bellonia

 * Artonis Hollow
 * Saffire Air Dockyard
 * Taron Power Station
 * Cold Quarry
 * Factorium

Philomenas

 * Darnic Village
 * Borru Catacombs
 * Mantide Caves
 * Aristel's Farm

Group Locations
Group instances are 1-5 player missions. More difficult than Squad instances.
 * Leunar Swamps
 * Mare Sacro Monastery
 * Targo Islands
 * Kuat-Lien Station
 * Fort Darlek
 * Tarlen Aquifer
 * Icy Plateau
 * Daren Facility
 * Hespilon Temple

Party Locations
Party instances are 1-10 player missions. Significantly more difficult than both Squad and Group instances.
 * Operation Isabella
 * Operation Medea
 * Operation Ophelia

Region/Open World
Region instances are open world maps where you can see other immortals who all have chains of quests to complete. At the end of completing all the quests, you will obtain a reward for liberating that Region from the locals(NPCs).

Unscaled/Regular

 * Red Coast
 * Antirius's Cave
 * Lanber Forest
 * Naori Island
 * Milene Caves
 * Laken Grotto
 * Usuni Valley
 * Isola Digs
 * Veines
 * Herder Temple
 * Eskenian Peninsula
 * Roqul Valley

Scaled

 * Antean Wastelands
 * Thea
 * Region Invasion/Infected Region