Just the dolphins who spawn in shipwrecks and ocean ruins will help you to find an ocean ruin or shipwreck but the rest of the dolphins that spawn naturally in the oceans are not going to help find an ocean ruin or shipwreck.
Linked issues
is duplicated by 2
relates to 1
Comments 11
Currently dolphins work by spawning in with a location to a structure. There are many reasons why this doesn't work and is ineffective.
Solution:
When feeding a dolphin the entity should search a radius of chunks/subchunks to see if any contain a {color:#59afe1}"LootTable":"anyloot"{color} nbt and give a "success sound" if any are found, then lead directly to the position or "fail sound" if none were found.
Since structures always spawn with chests containing LootTable NBT, and that LootTables don’t generate within anything outside of structures, I’m not sure it’s very necessary to have them specifically search for structures. (It’s just more efficient, but I also don’t see an issue searching for spaces containing structures so long as they also look for loottables).
The main reason I mentioned this is that Dolphins are meant to find treasure as the bug title implies, but not necessarily structures.
The behaviour as described in the description of this bug is the current intended behaviour in Minecraft: Java Edition.
Okay, after some thorough tests, I believe I've figured out the current behavior of dolphins in pre-6:
Dolphins will always lead to the nearest Ocean Ruin or Shipwreck unless distance < a certain amount, in which case it will search for the further of the two. Dolphins ignore the Y coord of structures, so they'll typically end up hovering over a structure location (this works almost identical to locate) and they also seem to ignore buried treasure structures, but this may be a bug.
Did you try that with naturally spawned dolphins, or did you spawn them yourself with a spawn egg?