Decided to share this ocean world, these are hard to find.
Works in 1.12.2 or higher. It was made in 1.10 few hours ago, can share this version too if someone wants it
Picture has the seed in the top left corner. Dunno does it work for you

World has really tiny islands wich are less than 20x20 blocks, ocurence - EXTREMELY RARE!
Default spawn has none, there is one nearby tho. But no tree
Few coordinates for islands that has a tree, tho there might be closer one

5368 64 5448
5450 66 4760
-10319 64 -9984
-5173 63 -4536

Found err round less than 10 or so tiny islands in a 10 000, 10 000 to -10 000, 10 000 area, tho i used mostly teleport with view distance of 30. If you happen to find any landmass that is considered normal size or bigger, please let us others know where it is

This map doesnt have any villages, mansions, temples etc above ground structures, including ocean monuments. All ores are found under level 63, stone variants too. Scaled down stone variants vein size too (were 33, now round 20)

Used mods are Optifine, Forge and VoxelMap