Aquaman is one of the most powerful superheroes in the DC Universe. This is not only true of his Atlantean superpowers, but also with regards to his political significance as the leader of the Earth's largest nation. In his fights, he has proven his mettle by clashing with Darkseid and the ocean gods from other worlds, while the sociopolitical reforms he has made to Atlantis have brought the isolationist underwater society into the 21st Century through a series of programs involving intercultural exchange with the surface world.
For all this, the crown weighs heavy upon his head. Aquaman lives with regrets, and like any moral monarch, some of his hard choices keep him awake at night. These are ten bad decisions he still regrets.
10 Accepting the Throne
Writer Geoff Johns reinvented the character of Aquaman when the DC Universe was rebooted in 2011 under the imprint of The New 52. All major events that Arthur Curry can regret, whether as part of his civilian life, his superhero career, or his life as the reigning King of Atlantis, emerge from this continuity.
This incarnation of the character was the daughter of an Atlantean queen and a human man. Eventually, Arthur Curry accepted his role as the heir to the throne of Atlantis, a traditionalist underwater society that resented having a half-human hybrid for a leader. While this was not the start of his troubles, it is where his life's troubles began to spiral out of control.
9 Spindrift Station
Dan Abnett began writing his excellent run of Aquaman by introducing Arthur Curry as a great diplomat working to bridge the xenophonic isolationists of Atlantis with the marginally-less-xenophobic Americans of the surface world. To do this, Aquaman had a new embassy constructed, Spindrift Station, where both cultures could mingle and exchange ideas.
Unfortunately, terrorists have a habit of attacking structures built to create peace. Thus it was that a cell of the Atlantean terrorist group, the Deluge, launched their attack on Spindrift Station, irrevocably harming the peace process.
8 Fighting Superman
When the US government decided to label Arthur Curry as a terrorist, they sent in military units to stop him. When infantry failed, they sent in tanks. When tanks also proved utterly useless against the Atlantean hero, they sent in Superman.
While Superman and Aquaman are both founding members of the Justice League, Arthur Curry's duty to serve his people creates diplomatic obligations that deny him the luxury of standing down. Superman tried to forbid Aquaman from leaving US soil. Aquaman responded by punching out the Kryptonian, reminding him who was a king, and who was just a cape-clad enforcer for the White House. This escalated things, complicating international diplomacy and causing friction between the two heroes.
7 Affair with Wonder Woman
The crossover event Flashpoint established a new timeline in which Aquaman had an affair with Wonder Woman, the Amazon princess killed Aquaman's wife Mera, and the two heroes destroyed half of Europe in a war between their nations. As armies of Amazon warriors under Wonder Woman's command clashed with the forces of Atlantis, the cost of reckless love became measured in bodies of the slain innocents caught between their forces.
Whether this continuity has been entirely wiped out seems to be debatable, but if it still exists within the DC Omniverse, then Aquaman certainly regrets sleeping with Wonder Woman given the calamitous fallout.
6 Graveyard of the Gods
Aquaman recently learned that one of his ancestors worked with Poseidon to betray the sea gods of other worlds. These gods were then sent to the mythical Graveyard of the Gods.
On a mission with the Justice League, the Atlantean King traveled there to try and make right the sins of his ancestor. Unfortunately, the gods of these other realms had learned not to trust Earth's people and their wrath could not be appeased. He lost everything during this mission.
5 Sparing Corum Rath
The terrorist leader Corum Rath is the head of the Deluge, an ethnonationalist Atlantean terror organization. This group blew up Spindrift Station and threatened the peace process between Atlantis and the surface world.
Rath later usurped the throne of Atlantis, cutting the kingdom off from the rest of the seas (and the world) while ordering the death of Arthur Curry. Letting Rath live after he attacked Spindrift Station was a dangerous decision and it resulted in Aquaman and Atlantis both suffering needlessly.
4 Arresting Vulko
Vulko is an Atlantean who is a loyal adviser to Aquaman. However, Vulko is a dangerously manipulative and cunning political operator, wise in the occult lore and Byzantine laws of Atlantis, but also operating with his own agenda.
Vulko saved Aquaman from the Dead King who tried to take over and then destroy Atlantis. Despite this, Vulko was jailed, as he was not someone Arthur Curry could trust. Had Vulko not been imprisoned, he could have helped Aquaman avoid succumbing to the dangers of that beset him on all sides, even preventing Corum Rath's coup.
3 Arresting His Brother Orm
Orm is Aquaman's brother and spent some time as the King of Atlantis. He launched an attack against the surface world during the events of the Throne of Atlantis story, flooding the east coast of the United States with massive tidal waves that killed thousands.
Aquaman allowed the surface world to jail his brother. However, Orm eventually escaped and though he seemed like he might actually be reformed, it was not long until he once again began scheming and causing trouble, becoming entangled in power struggles for control of Atlantis.
2 Revisiting The Diner
As a boy, Arthur Curry used to live with his father at a lighthouse in Amnesty Boy. Years later, he returned to his home town as an adult, now known the world over as the superhero Aquaman who helped found the Justice League.
In the debut issue of his series in The New 52, he went out to eat at a local diner where he and his dad used to have meals when he was a boy. While he had hoped to enjoy a quiet meal and some fond memories, the patrons asked him mocking questions, like whether he talked to fish. He never got to enjoy that quiet meal he hoped for, but at least he left a good tip for the waitress.
1 Bombing Tethys
The planet Tethys is a world covered by water. During the four-part story "H2.0." The planet is made of a sentient form of water and successfully makes contact with Earth via a deep-sea portal in the Gulf of Mexico.
Unfortunately, the water from Tethys transformed humans into predatory aquatic monsters. During an unfortunate series of events that rapidly spun out of control, Aquaman tried to save some such humans and disarm a bomb that was about to go off by dropping the bomb into the portal, attacking an innocent alien entity. He might have saved a few human lives, but he attacked a whole civilization that just wanted to make contact. In the aftermath of this, Mera chides him for acting like a surface dweller, abandoning the diplomacy he claims to value so much.