If you want an easy way to get tresure maps then spread the coruption (Unholy water) on to the ocean and get like 10 or 15 worm food and keep killing eater of world's and you should get alot from this.
This is what I do: https://i.imgur.com/GV8DvKA.jpg You just put in the biomes of your choice, I imported both corruption and crimson blocks from other words. Then put jungle blocks there because mob spawn rates increase in the jungle biome. This setup farms keys and treasure maps, just stand in the pool of water inside the house so any water monsters will think you are in the water and go to you, then your minions can kill them while you AFK. If you want to kill them yourself, you can put platforms around the pool of water instead of solid blocks but that will make arapaimas jump out of the water and attack you, which is bad for AFK. Putting platforms under the house in the water will help prevent the drops from falling to the ocean floor.
I recommend if on hard to get traps from lizard temple and set the spike ball around you on a one sec timer and you in an closed box with 50 meteor around on both sides over the ocean or in any other bioms for other key molds.
Y=You X=spike ball trap Z=Meteor blocks 50 each Box 1/2=Any block Meteor heads will spawn around you and die from the traps and will drop stuff if needed you can add dart traps on both sides of you need