The Cosmic Completionist trophy/achievement will require you to discover every single named location in the game and will also get you the I Come From The Land Up Over , Beam Me Up , and Eridian Explorer . Some tips that help include doing every optional mission possible, as some locations are locked for those optional missions, like Lab 19 in Research and Development only showing up when you do the mission of the same name.

Also, some maps may appear as if you’ve visited every location, but don’t be deceived by that. Two big culprits of this are the East Pumping Station in Vorago Solitude and Compression Chamber in Tycho’s Ribs. Both of them appear as if you’ve been there (the map is revealed), but they are often overlooked because players don’t visit and see the names of those areas pop up on your screen.

Serenity’s Waste locations

• Ozless Harbor
• Celestial Beltway
• Pyroclast Grotto
  Pyroclast Grotto is the location of the secret boss, Iwajira. Take the top exit from Janey’s place and jump onto the large cable-like things protruding from the building. You want to find a ledge that will lead into a cave with lava, which you will follow to a hole in the ground that is Pyroclast Grotto.

Triton Flats locations

• Wreck of the Dundee
• Diaphragm
• Lunar Junction
• The Pale
• Spitfire Pass
• The Grabba
• So Much Serenity
• Shimmer Island
• The Causeway
• The Teapot
• Vertigo Bridge
• Burraburra
• Diemen’s Crater
• Guttersnipe Pass
• Troll Booth
• Flinder’s Needle
• Banjo Point
• Bradman’s Quarry
• Frozen Gulch
• Chunder’s Hole

Stanton’s Liver locations

• Stanton’s Gate
• Stanton’s Liver
• The Duct
• St. Pancreas
• The Ventricles
• Higgin’s Gully
• Piraud’s Trutch
  When you visit Higgin’s Gully, you will see a purple monolith in the middle of it. Run straight into it and you’ll appear in the Piraud’s Trutch area, with another monolith, which will bring you into small room with a chest and one more monolith that will bring you back to Higgin’s Gully.

Hyperion Hub of Heroism

• World of Shopping
• Road to Research
• Helios Immigration Station
• Central Terminal
• Helios Access Tunnel 27
• Harren Lockup
• Hall of Wonders
  Jack’s Office is also part of this trophy/achievement, but considering you visit it multiple times during the story, it’s not listed here because it’s impossible to miss.

Veins of Helios

• Central Maintenance
• Plasma Facility A
• Plasma Facility B
• Remote Access Platform
• Supply Platform

Lunar Launching Station

• Moonshot Supply Depot
• Laser Command Center
• Power Core Beta
• Power Core Alpha
• Helios Targeting System
• Laser Amplification Nexus

Research and Development

• Research and Development
• Indigenous Species Research
• Advanced Propulsion Weapon Testing
• Stalker Biome
• Observation Room 11b
• Aquatic Observation Area
• Aquatic Life Stabilization Area
• Robotic Durability Research
• Lab 19
• De Quid Synaptic Process
• Weapon Assembly

Outlands Canyon

• Fingersmith Halls
• Bogan’s Warren
• Seymour’s Silo
• Crater of Misplaced Enthusiasm
• Rabid Adam’s Treasure Trove
• The Re-Remembered Cave
• Research Facility
• The Court of Dreams

Outlands Spur

• Outlands Spur
• Processing Plant
• Height’s Perch Camp
• Pumping Station
• Cave Canem

Vorago Solitude

• Vorago Solitude
• Solitude’s Edge
• East Pumping Station
• Solitude Junction
  East Pumping Station is located by The Don, who gives out the optional mission of the same name.

Regolith Range

• Dead Drop
• Deadlift’s Bastion of Bounce
• Kraggon Pass
• Dahl Waystation
• Moon Zoomy Run

Crisis Scar

• Comms Facility
• Power Substation
• RedBelly Arena

Pity’s Fall

• Drakensburg Gate
• Drakensburg Gangway
• Core Systems
• Suspension Bridge
• Command Center
• AI Hub
• Security
• Crew Quarters
• Starboard Ascent
• Hangar Bay
• Briefing Room
• Engine Room
• Engineering
• Shattered Aft

Titan Industrial Facility

• Titan Transportation Hub
• Stingray Factory: Apron
• Stingray Factory: Atrium
• Stingray Factory: Main Hall
• Industrial Facility: Nexus
• The Robot Production Plant: Entrance
  Sub-Level 13 is also a part of this and you will go there whenever you do the Sub-Level 13 optional missions.

Titan Robot Production Facility

• Core Systems
• Power Control
• Oculus Lab
• Assembly Hangar
• Testing Facility
• Locomotion Assembly
• Transit Area
• Unit Embarkation

Tycho’s Ribs

• Observation Deck
• Compression Chamber
• Particle Collection Chamber
• Maintenance Access #42
• Exhaust Port
  Note that Eleseer and The Vault are included in this, but they are visited during the main story and impossible to miss.