Minecraft cool single survival island seed 1.15.1 with ocean ruins
There are actually ocean ruins on the southwest side of the island, just swim down and you'll find it. There's coal and wheat in the treasure chest and a leather tunic. Very cool seed for Minecraft.
The seed is: -4830098514377867107
As for the Minecraft survival island seed itself, there are a lot of trees and the start of a cave that makes an excellent place to setup a home. There's an exposed coal vein on the southeast corner of the island and down in the natural cave you can find an exposed vein of iron. This is one of the best Minecraft seeds hands down. Finally we found a single lonely island to add to the list of Minecraft island seeds.