When you first look at it, the Golarion map looks pretty big! Multiple climatic regions, oceans and deserts, all the trimmings. BUT after Jade Regent came out, everyone realized that there was a LOT more Golarion than just the Inner Sea region…
Golarion is modeled after Earth, meaning it is the same size, has one moon with the same orbit, and so on. This decision greatly simplified the world design, since the creative team at Paizo did not have to include a number of scientific experts to figure out how their world worked (e.g., geology, tides, climate, solar and lunar cycles).
The Prime Meridian runs through Absalom.
The Tropic of Cancer runs through the Mana Wastes.
Magnimar is at the same latitude as Seattle, Washington, USA though it can shift south towards Portland, Oregon, USA if needed to make the rest of the map work out.
There is several hundred miles of unmapped tundra between the Stormspear Mountains at the northern edge of the Linnorm Kingdoms and the Rimethirst Mountains at the Crown of the World.
Basically, the Inner Sea is small and the planet is, well, rather large. The Paizo forums, as you can imagine, went nuts, but it was a very cool thing and ultimately resulted in Spinning Golarion Globe.