terrain.border_paddingIsland shape
What it does
Pushes a ring of guaranteed open ocean in from the map edge. Each 0.1 is about 5% of the map width forced under water — the whole island slides inward to make room.
What you seeRaise it and a widening moat of ocean appears around the rim while the island shrinks; go negative and land runs right off the playable edge.
Gotcha
There's no safety limit — values near 1 drown almost the whole map. Negative values (like -0.6) push land past the playable edge, which is how full-square flat maps are made.
See it on a real map
Reference seed 12345, size 4500. “Try live” opens the generator with the value applied.
default 0.0
0.2 — wide ocean try live →
0.5 — tiny island, half-map sea try live →
-0.6 — land to the edge try live →