The place where you spawn is near a large ocean biome. When diving, you can see many eye-catching coral structures. It is considered as a big coral that’s worth discovering in Minecraft. Take Potion of Water Breathing and Potion of Night Vision before exploring the underwater world.
How to Play Huge Coral Biome At Spawn (Beta Only) Seed
After spawning, you should come back to the spawn until you find a big ocean biome. The corals appear under the water.
These images below tell you the overview of this seed.
Watch the following video to know how the seed works clearly.