@Emma Okay so Carthus is located in the North Eastern hemisphere with High Mist below it occupying parts of the Northern Hemisphere, the Equator and the beginning of the South Hemisphere. Completely south of that is Crysteria (very similar to Antarctica in location).
Then there is a huge gap of uncharted waters (this is the Oceana Abyssal) to the west of Carthus and High Mist (ships cannot traverse these waters). The only way to get to Valenndale and Penault is to sail east (which can be very inconvenient, especially for Dwarven trade).
Valenndale and Penault are on the Western Hemisphere, with Valenndale being North and Penault being south (with bits of it bordering the equator.
So if we were to compare it to a real-world map:
Carthus = Europe/Asia
High Mist = Africa
Valenndale = North America
Penault = South America
Crysteria = Antarctica
Unfortunately there is no Australia :(