One peaceful day, turned into a very Violent one when Hades became jealous of his brothers above, and decided to show his anger to the world. He erupted volcanoes all over the place.
The 2 Brothers came to confront Hades about all the wreckage above. Zeus and Poseidon asked Hades what was wrong, he said he was tired of being separate from the world, and being with all the dead souls, while his brothers got to live wonderful lives in the world above him.
So Zeus and Poseidon took Hades up to their world to make Hades feel better, First to Mount Olympus to show Hades where all the Gods lived.
Then Poseidon lead him down to his ocean realm where Hades could see all the Fish, and creatures of the water
that he got After Hades tour of the world above him, He felt better that he got to take a break from all the souls and darkness. All the lava and magma turns to ashes as their moved to Mount Olympus, he heads back to his realm and the other brothers back to theirs
The volcanoes stayed though, hoping to be an interesting new land feature to the Earth, and all was well.