I've built a bridge from the starter island across a bit of an expanse to a second island. Took a bit of stuffing around. Its approximately 8 full length horizontal core woods long and then probably another 4 of those each side of the bridge I tried raising the ground as much as I could before I couldn't reach the bottom of the water anymore. Hard to explain but basically I made a bridge to another island which would be about a fog diameter, I think