Minecraft allows you to create structures naturally. Most of these structures have loot boxes. There are many of them in Minecraft, but very few can be found underwater.
Potions of night vision or water breathing are helpful when exploring underwater structures. The player will likely be submerged for quite some time. A helmet enchantment called Respiration can also be useful.
You can see cold ocean ruins in all ocean biomes, including those that are frozen, normal, or deep. Warm ocean ruins can be created in warm, cold, or deep lukewarm seas. While cold ocean ruins consist of stone blocks and warm ocean ruins, they are made from sandstone or stone.
They can be varied in size, with only 30% being generated from large ocean ruins. Loot chests in ocean ruins can contain valuable items like emeralds and golden apples, as well as some valuable loot. The ocean ruins are dangerous because drowneds can be found in and around them.
One of the most common underwater structures is shipwrecks. These sunken ships are missing parts or multiple blocks. They can hold up to three chests, depending on their size. These chests can contain rare loot items like diamonds or emeralds.
There is a 100% chance that their chests will contain a treasure map, which can be used to locate hidden treasure. Shipwrecks can be found in all oceanic biomes, and sometimes even close to or above shores.
Ocean monuments can be found in deep sea biomes, as well as other variations. They are the largest Overworld structures in Minecraft. Ocean monuments are the only source for sponges as they can't be crafted and cannot be generated anywhere else.
The ocean monument is dangerous and should not be explored by beginners. Guardians and Elder Guardians can cause a lot of harm. Each monument has three elder guardians and countless guardians. They naturally continue to spawn there.