Travelling
Travlling in Eorzea and beyond is done by various means, the most expensive of them being the Aetheryte network. There are a number of cheaper - and not much more complicated - ways to get around.
Yet if you haven't been in a place for some time, it might escape your mind how you got there in the first place, like the Crystarium or Thavnair. But let's begin at the beginning...
Means of Travel
Chocobo porters
In the early zones, the Chocobo porters are a very valuable choice. They cost a lot less than a full Aetheryte travel if you're not that far away, e.g. from Gridania to the South Shroud, it's about a tenth of the gil you'd spend on the Aetheryte travel!
The two downsides are: You can not go from any point to any point (you can go to any porter of a region from the central city, but you cannot go between any two porters of a region), and you actually do ride the journey (but you don't have to actually watch it).
Sadly, later on the cost for the Chocobo porters is very out of balance with the level of convenience (and you're not that tight on gil), so you'll hardly use them in Heavensward and afterwards.
Aetheryte
(This is about the "big" Aetherytes which show on the maps and are reachable from everywhere. The other, "small" ones in the cities are called Aetheryte shards, you can only hop between them when you're in the city.)
You get two "free destinations": Your "Home Aetheryte" and your "Free Aetheryte". Both allow you to travel to them (via Return resp. Teleport) without any gil cost. The difference is that the Free travel has no cooldown, the Home travel with "Return" can only happen once every 15 minutes. Beyond those, you get "favored" destinations (without a cooldown): Those allow you to travel at a 50% discount, which can mean up to around 500 gil if you travel from one end of the world to the other (or smaller chunks to save, but frequently: hubs you return to often).
All those options are in the following called "discount destinations".
Starting zone / Questing zone: Home and Free
It's advisable, due to the cooldown of "Return", to put the Home point on the Aetheryte in your "home town" (where you are get called back to from time to time, as your class/job quests and the MSQ make use of it), and your Free point to the zone you're currently questing in (where you can use it for frequent quest turn-ins). You can also set one of your Favored destinations on top of the Home destination to avoid excessive spending, if you feel the urge to move back and forth quickly and don't want to wait for the cooldown.
You shouldn't (feel the need to) spend any gil on Aetherytes at least for your first twenty levels.
discount tickets for Aetheryte travel
Later on, there are various ways to get discounts on Aetheryte travel:
- scrolls for one trip to a specific Aetheryte, e.g. from your Company
- scrolls to reduce travel cost for a duration, e.g. from Squadron Missions
- scrolls for one free trip, e.g. a very few from the MSQ
Airships
Between most major cities, airships are the way to fly. There seems to be a limit of distance for the machines, because Kugane is only airship-reachable from Radz-at-Han. Garlemald itself is reached via a local airship route not connected to the other cities.
Ferries
To islands and between islands, ferries are the way to float.
Limsa Lominsa, Old Sharlyan and Kugane in the Far East qualify. Thanvair, despite being an island by itself and highly dependable on import/export via boats, doesn't.
Limsa Lominsa is the central connecting point for those destinations, it connects to Eorzea in Western Thanalan, and it even has local ferries to Western/Eastern La Noscea at a very reasonable price.
Locations and how to reach them
Major cities & the Gold Saucer
The starting cities (Gridania, Limsa Lominsa and Ul'dah), Ishgard and Radz-at-Han are directly connected via airships. Kugane can be reached from Radz-at-Han directly and only there. (The Crystarium is its own world.)
In the starting cities, the access is at an own Aetheryte shard "Airship landing", in two cities forcing you to take an elevator to get to a workable Aetheryte shard. Later on it's some "regular" place, i.e. an Aetheryte shard that's not "special". Look for this icon: (airship landing icon)
It's worth to note that travelling to the Gold Saucer from any starting city is free - and travelling to Ul'dah from the Gold Saucer is also free! It's therefore advisable to unlock the Gold Saucer, even if you're not interested in the games there, to save the airship travel cost for Ul'dah entirely.
Vesper Bay & Mor Dhona
Initially, the first money saver for travels are the free passes you get from the MSQ to get to Vesper Bay. If you used those up (or want to save them up to use them later strategically for longer distance travels), it is - surprisingly - faster to go to Vesper Bay via Limsa Lominsa: There is a ship going from the port (Aetheryte: Arcanist's guild) to Vesper Bay right next to the Waking Sands for 80 gil. The way the MSQ leads you, you would instead set a "discount destination" to Horizon, but have to fly (or take the ride, the porter is tolarably expensive) from Horizon to get to the Bay itself.
Similar to Vesper Bay, you get a bunch of Aetheryte tickets for Mor Dhona, but not that many. This is a favored destination to stay: You will come back to this place often.
Kugane (in Othard, the "Far East" of Stormblood) & Old Sharlyan (& Labyrinthos / Ultima Thule)
Kugane is the first time where you MUST use a ferry for 300 gil to get to, meaning if you were at 0 gil, you couldn't get there at all. The ferry for Kugane and for Old Sharlyan leave in Limsa Lominsa at the port near the Arcanist's guild Aetheryte shard. There is no discount on ferries, so having one of the Home/Free points in Kugane resp. Old Sharlyan (or beyond) while you are levelling there is highly advisable. From Old Sharlyan, you get on to Labyrinthos (from any Atheryte shard) and from there to Ultima Thule (where the space ship was parked).
Crystarium (in Norvrandt, the First of Shadowbringer) & Thavnair (the "Almost As Far East" of Endwalker)
Crystarium and Thavnair are special: There is no ferry nor any other means of land travel. (On the up side, the available options don't incur extra costs, unlike Kugane / Old Sharlyan.)
For the Crystarium, you head to Mor Dhona, then into the Syrcus Trench by talking with the Saint Coinach Ferryman, in the trench the Beacon Keeper helps you to move forward. This also works in the other direction, you can enter the Syrcus Trench from the Ocular, and from the trench you get back to Mor Dhona.
For Thavnair, there is one way "Aetheryte travel for free", if you hop to Old Sharlyan and run north-west from the main Aetheryte. (It's how you get to Thavnair in the first place, by being an "Aetheryte travel guinea pig". That option is not bound to the quest!) There is no way back from Thavnair to Old Sharlyan: If you run out of "discount destinations" it's therefore advisable to set one destination to Old Sharlyan, NOT to Thavnair. (While you quest, Old Sharlyan should probably be either your Free or your Home destination.)
Garlemald
For Garlemald, you move to the Lochs in Gyr Abania (by whatever means). In the Ala Mhigan Quarter talk to (...) to cross the border. On the map, it has the airship landing icon, though this is unlike the other airship landing points, as the place doesn't look like it. (It's in the middle of the city, nothing looking like an airport.)