Aquaman's troubles spawn from the 1970s cartoon Superfriends. The line-up was as follows:
Superman: Last Son of Krypton. Strong, flies, see through things, invulnerable.
Batman: World's Greatest Detective. Smart, charming, skilled.
Robin: The Boy Wonder. Batman's sidekick, and you don't expect greatness from a sidekick; not crying in front of the villains is a victory.
Wonder Woman: The Original Warrior Princess. Strong, agile, beautiful, and had an invisible jet.
They were later joined by:
Green Lantern: The Man Without Fear (no wait, that's Daredevil.) Space-magic ring that lets him create anything he can imagine (which makes his usual usage of giant boxing gloves rather sad.)
Flash: The Fastest Man Alive. Superspeed. Running fast doesn't seem like much of a power, but he's versatile.
Hawkman: Guy Dressed Like A Bird. Flight (via wings)
...and three Hanna-Barbera creations, all "Captain Diversity":
Black Vulcan: Black guy with lightning powers
Apache Chief: Native American guy with growth powers
Samurai: Japanese guy with wind, fire, and invisibility powers
(There was also Marvin/Wendy/Superdog, and the Wonder Twins with Gleek. And that is the last I shall mention them.)
Then there was Aquaman. Aquaman wasn't thought through very much, so he was essentially a normal guy who could breathe underwater and talk to fish. Had that been thought through, they would have realized three things:
1) Aquaman is undisputed lord and master of 75% of the planet.
2) Aqauman talks to things such as whales (not fish, but he can), sharks, giant squids, and dolphins (can you say espionage?)
3) Aquaman can survive the Marianas Trench. That alone has to grant him enormous strength and durability.
Combine this, and he should have been curb-stomping villains, feeding them to sharks, and claiming diplomatic immunity when called on it!