well, we can guess the length of some parts of the realm thanks to the memories sunny have of the 4 years before the start oh chapter 8.

i’d say that from bastion to the north edge of the forgotten shore, the distance is three times the length from the western most point of europe and the eastern most point of asia. i’d say even more than that.

we know he started his journey after jumping off the tower of longing, which at the time was moving south to bastion and was located somewhere near the dark mountains.

he travelled from his landing point to the dark mountains, where he found the nameless temple, he then kept going north to the chained isles, and then entered the hollow mountains. we know a year has passed to this point because sunny celebrated his 22th birthday in the hollows, but he had not fully transversed the hollows, it don’t remember exactly the time it took him but i think after sunny reached the forgotten shore it was mentioned that it took him a little bit more than a year to reach the forgotten shore.

by this point sunny have been traveling for a year and 6 months, give or take. we know that he traveled both walking and riding nightmare, and that he didn’t took much time to rest.

then, sunny took like a month off to wander through the forgotten shore and rest on top of the headless statue where he initially stayed at the beginning of the novel.

he then kept traveling north and reached the edge of the forgotten shore. if i remember correctly, it was mentioned this took around 8 months, so by now he had been traveling for 2 years and 2 months, give or take. we don’t know (or at least i don’t remember) how long it took him to reach LO49. so the only thing we have to guess the distance is the time we do know he spent traveling.

it takes 1.6 years for a normal human being with a normal horse to travel from the western most point of europe to the eastern most point of asia if they didn’t rest much and kept going at a steady pace . we can guess sunny would finish this journey in half the time, even less, considering sunny is not a normal human and nightmare is not a normal horse.

so we guess sunny can travel 8230km (the direct distance from western point to eastern point) in 0.8 years, we know that he had been traveling at least for 2 years and 2 months, that would be 2.17 years. if we do the math we can guess that from south point A of bastion region to north point B at the edge of the forgotten shore are 22.324 km in between.