This seed allows you to spawn on a nice survival island that provides an abundant source of trees. Therefore, you can use the trees to set up your base and create your safety gears.
There is a mineshaft under the island, and it connects to the island by a dungeon.
How does Survival Island With Mineshaft & Dungeon Seed work?
Look at the red circle below. You have to dig down the blow with a red circle to recognize the mineshaft.
A tunnel will appear after you spend some minutes for digging.
Turn left and go ahead. You no longer find the dungeon connecting to the mineshaft.
A big plus of the game is that it has a mob spawner, which helps you kill zombies and obtain valuable loot.