What are the requirements to get the floor jump?

I was exploring Floor 14 and found the stairs going down to floor 15 but the floor jump didn't become enabled. now i know there was a couple of islands i hadn't mapped but i was quite sure i had mapped every possible way to the stairs

• i had found both ways to reach the island where you meet the Forrest girl

• mapped the entire southern part of the map

• mapped the most of the eastern part except for the island with the 2 alligators

• i put one of those pink flowers at every one of those flowers which you can use that i could see and an arrow in the direction it would go

• land i marked with green tiles while water i marked with blue

So i am wondering, what exactly are the requirements of getting the floor jump unlocked?